Projection exposure apparatus and method

ABSTRACT

The present invention relates to a projection exposure apparatus ( 10 ) for and method of imaging a reticle (R) having patterned surface onto a substrate (W) in photolithographic processes for manufacturing a variety of devices. The invention further relates to an optical system (C) having a folding member (M 1 ) suited to the projection exposure apparatus, and a method for manufacturing the optical system. The projection exposure apparatus comprises an illumination optical system (IS) and a reticle stage (RS) capable of holding the reticle so the normal line to its patterned surface is in the direction of gravity. The apparatus also includes a substrate stage (WS) capable of holding the substrate with its surface normal parallel to the direction of gravity. The optical system includes a first imaging optical system (A) comprising a concave reflecting mirror and a dioptric optical member arranged along a first optical axis. The first imaging optical system (A) forms an intermediate image of the patterned surface. The optical system also includes a second imaging optical system (B) having a second optical axis, and forms a reduced image of the intermediate image on the substrate. The first folding member is arranged in the optical path from the first imaging optical system to the second imaging optical system. The first and second imaging optical systems and the first and second folding members are positioned so that a reduced image of the pattered surface is formed parallel to the pattern surface of the reticle, and the first and second optical axes are positioned so that they are substantially parallel to the direction of gravity.

FIELD OF THE INVENTION

[0001] The present invention relates to a projection exposure apparatusand method used when transferring a projection master plate (mask,reticle and the like) onto a substrate in photolithographic processesfor manufacturing devices like semiconductor devices, image pickupdevices, liquid crystal display devices and thin film magnetic heads,and further relates to an optical system having a folding member suitedto the projection exposure apparatus, and a method for manufacturing theoptical system.

BACKGROUND OF THE INVENTION

[0002] In photolithographic processes for manufacturing semiconductordevices and the like, a projection exposure apparatus is used thatexposes the pattern image of a photomask or reticle (hereinafter,collectively referred to as “reticle”) as the projection master plateonto a substrate (wafer or glass plate and the like) coated with aphotosensitive material like photoresist via a projection opticalsystem.

[0003] With the increase in the level of integration of semiconductordevices and the like in recent years, the resolving power required byprojection optical systems used in projection exposure apparatuses hasbeen rapidly increasing. To meet this requirement, it has becomenecessary to shorten the wavelength of the exposure light and toincrease the numerical aperture (NA) of the projection optical system.However, if the wavelength of the illumination light is shortened,particularly below 300 nm, the number of types of glass materials thatcan be used for practical purposes is limited to a few due to theabsorption of light. Accordingly, the correction of chromatic aberrationbecomes problematic if the projection optical system is constructed withjust dioptric optical elements. In addition, a dioptric optical systemrequires numerous lenses to correct the Petzval sum.

[0004] In contrast, a catoptric system not only has no chromaticaberration, but can also easily correct the Petzval sum by the use of aconcave reflecting mirror. Accordingly, the construction of projectionoptical systems with so-called catadioptric optical systems that combinea catoptric system with a dioptric system has heretofore been proposed.Such catadioptric optical systems have been proposed in, for example,U.S. Pat. No. 5,537,260, U.S. Pat. No. 4,747,678, U.S. Pat. No.5,052,763 and U.S. Pat. No. 4,779,966.

[0005] An increase in the NA and exposure region of projection opticalsystems has been demanded in recent years, and the aperture diameter ofthe optical members that constitute catadioptric optical systems haslikewise increased. In light of the resolution required by projectionexposure apparatuses, the effect of deformation of large optical membersdue to gravity cannot be ignored. A catadioptric optical system may beconstructed with optical members in which the direction of the opticalaxes is not identical, as is typical of the prior art. One or more suchoptical members having power tend to be deformed asymmetrically withrespect to the optical axis. This gives rise to asymmetric aberrations,which are difficult to correct during manufacturing, making it difficultto obtain sufficient resolution.

[0006] When correcting chromatic aberration in a conventionalcatadioptric optical system, high-order chromatic aberrations liketransverse chromatic aberration, cannot be sufficiently corrected withjust a concave reflecting mirror and quartz glass, and the image sizecannot be increased. Consequently, attempts are being made to realizesatisfactory correction of chromatic aberration over the entire exposureregion by forming a number of lenses with fluorite. Nevertheless, sincethe volume and refractive index of lenses made of fluorite change muchmore than quartz glass and other optical glasses when environmentalfactors, like temperature, change, the optical performance ofconventional optical systems deteriorates greatly when the environmentalconditions fluctuate.

[0007] Catadioptric optical systems and catoptric optical systemstypically require the use of a folding member to separate the opticalpath of the going path toward the concave mirror from the optical pathof the returning path from the concave mirror. As a result, a pluralityof partial optical systems having mutually different optical axesbecomes necessary, and it follows that a plurality of lens barrelshaving different axes becomes necessary. Consequently, there is theproblem that, compared with dioptric optical systems, errors are easilygenerated in the adjustment between the plurality of optical axes whenassembling catadioptric optical systems and catoptric optical systems.In addition, even after assembly, the stability is poor due to thecomplex construction, and the positional relationships between opticalaxes gradually deviate, creating a tendency for the image todeteriorate. In addition, the folding member has an incident opticalaxis and an exit optical axis, which are not formed symmetrically. Forthis reason, rotating the folding member about the incident optical axisor about the exit optical axis due to, for example, factors likevibration, causes rotation of the image. In addition, rotating thefolding member about the axis orthogonal to both the incident opticalaxis and the exit optical axis causes distortion of the image, making itdifficult to stably obtain an image of high resolution.

[0008] Furthermore, optical adjustment of a dioptric optical system isdisclosed in U.S. Pat. No. 4,711,567 and Japanese Patent ApplicationKokai No. Hei 10-54932, and optical adjustment of a catadioptric opticalsystem is disclosed in U.S. Pat. No. 5,638,223.

SUMMARY OF THE INVENTION

[0009] The present invention relates to a projection exposure apparatusand method used when transferring a projection master plate (mask,reticle and the like) onto a substrate in photolithographic processesfor manufacturing devices like semiconductor devices, image pickupdevices, liquid crystal display devices and thin film magnetic heads,and further relates to an optical system having a folding member suitedto the projection exposure apparatus, and a method for manufacturing theoptical system.

[0010] Accordingly, the first goal of the present invention-is toprovide a large numerical aperture in the ultraviolet wavelength region,and to achieve high resolution without any substantial impact of gravityand the like.

[0011] The second goal of the present invention is to achieve a largenumerical aperture in the ultraviolet wavelength region and a largeexposure region, and to achieve an optical system of a practical size,satisfactorily corrected for chromatic aberration over the entireexposure region, having stable optical performance even duringenvironmental fluctuations, and having a high resolution.

[0012] The third goal of the present invention is to make the opticaladjustment of an optical system having a plurality of optical axes easy.

[0013] The fourth goal of the present invention is to reducedeterioration in imaging performance even after an optical system havinga plurality of optical axes is assembled.

[0014] The fifth goal of the present invention is to perform with highprecision optical adjustment of an optical system having a foldingmember.

[0015] Accordingly, a first aspect of the invention is a projectionexposure apparatus for exposing a mask having a patterned surface onto asubstrate having a photosensitive surface. The apparatus comprises anillumination optical system, and a reticle stage capable of holding thereticle so that the normal line of the patterned surface issubstantially in the direction of gravity. The apparatus furtherincludes a substrate stage capable of holding the substrate so that thenormal line of the photosensitive surface of the substrate issubstantially in the direction of gravity. The apparatus furtherincludes, between the reticle and substrate stages, a projection opticalsystem comprising first and second imaging optical systems. The firstimaging optical system comprises a concave reflecting mirror and adioptric optical member arranged along a first optical axis, and isdesigned to form an intermediate image of the patterned surface. Thesecond imaging optical system has a second optical axis and forms areduced image of the intermediate image onto the photosensitive surface.A first folding member is arranged in the optical path from the firstimaging optical system to the second imaging optical system, and isprovided with a reflecting surface having a reflective region that issubstantially planar. Also, a second folding member is arranged betweenthe first folding member and the second imaging optical system, and isprovided with a reflecting surface having a reflecting region that issubstantially planar. The first and second imaging optical systems andthe first and second folding members are positioned so that a reducedimage of the pattered surface is formed parallel to the pattern surfaceof the reticle, and the first and second optical axes are positioned sothat they are substantially parallel to the direction of gravity.

[0016] A second aspect of the invention is a method for exposing apattern on a reticle onto a substrate. The method comprises the steps offirst illuminating the reticle, then projecting an image of the reticlewith the projection exposure apparatus as described immediately above,and then exposing the pattern over an exposure region having either aslit-shape and arcuate shape, wherein the exposure region does notinclude the optical axis of the second imaging optical system in theimage plane. In the exposure process, it is preferable to simultaneouslyscan the reticle stage and the substrate stage.

[0017] A third aspect of the invention is a projection exposureapparatus for forming an image of a first surface onto a second surface.The apparatus comprises a projection optical system having a lens, aconcave mirror, a folding member and two or more optical axes. Anoptical member is arranged along each of the two or more optical axes,each optical member being held by a barrel provided along each of thetwo or more optical axes. Each of the barrels includes one or more lensbarrel units each having one or more lens assemblies (or alternatively,lens elements) designed so as to be inclinable and translatable withrespect to the optical axis. Also, at least one of the barrels isprovided with at least one adjustment apparatus capable of inclining andtranslating the at least one barrel with respect to the optical axispassing therethrough.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1a is a schematic diagram of the projection exposureapparatus according to the present invention;

[0019]FIG. 1b is a plan view showing the exposure region EA on wafer Wfor the apparatus of FIG. 1;

[0020]FIG. 2 is an optical path diagram of the catadioptric opticalsystem according to a first mode for carrying out the present invention;

[0021]FIGS. 3a, 3 b are plots of the shape of the aspherical surfacesprovided in the catadioptric optical system of FIG. 2, wherein thehorizontal axis is the distance from the optical axis in mm and thevertical axis is the deviation from an approximately spherical surfacein mm.

[0022]FIGS. 4a-4 f are aberration plots of the catadioptric opticalsystem of FIG. 2, wherein FIG. 4a is a lateral aberration plot in themeridional direction at an image height Y of 17.1 mm,

[0023]FIG. 4b is a lateral aberration plot in the meridional directionat an image height Y of 11 mm,

[0024]FIG. 4c is a lateral aberration plot in the meridional directionat an image height Y of 5 mm,

[0025]FIG. 4d is a lateral aberration plot in the sagittal direction atan image height Y of 17.1 mm,

[0026]FIG. 4e is a lateral aberration plot in the sagittal direction atan image height Y of 11 mm, and

[0027]FIG. 4f is a lateral aberration plot in the sagittal direction atan image height Y of 5 mm;

[0028]FIG. 5 is an optical path diagram of the catadioptric opticalsystem according to a second mode for carrying out the presentinvention;

[0029]FIGS. 6a, 6 b are plots of the shape of the aspherical surfacesprovided in the catadioptric optical system of FIG. 5, similar to thosein FIGS. 3a, 3 b;

[0030]FIGS. 7a-7 f are aberration plots of the catadioptric opticalsystem of FIG. 5, wherein

[0031]FIG. 7a is a lateral aberration plot in the meridional directionat an image height Y of 17.1 mm, FIG. 7b is a lateral aberration plot inthe meridional direction at an image height Y of 11 mm, FIG. 7c is alateral aberration plot in the meridional direction at an image height Yof 5 mm, FIG. 7d is a lateral aberration plot in the sagittal directionat an image height Y of 17.1 mm, FIG. 7e is a lateral aberration plot inthe sagittal direction at an image height Y of 11 mm, and FIG. 7f is alateral aberration plot in the sagittal direction at an image height Yof 5 mm;

[0032]FIG. 8 is a cross-sectional view of the support structure andoptical elements of the projection optical system according to a thirdmode for carrying out the present invention; FIGS. 9a-9 c show the firstto third barrels, respectively, according to the third mode for carryingout the present invention, wherein FIG. 9a is an oblique view of thesecond barrel,

[0033]FIG. 9b is an oblique view of the first barrel, and FIG. 9c is anoblique view of the third barrel;

[0034]FIG. 10 is an oblique view of the upper and lower frames, and themain support for the projection optical system of FIG. 8;

[0035]FIG. 11 is an explanatory diagram showing the relationship betweenthe center of rotation and the image deviation of the imaging opticalsystem;

[0036]FIGS. 12a, 12 b show the projection optical system and the supportstructure thereof according to a fourth mode for carrying out thepresent invention, wherein FIG. 12a is an XY plan view, and FIG. 12b isa longitudinal cross-sectional view (YZ cross-sectional view);

[0037]FIG. 13a is a partial cross-sectional front view (YZ partialcross-sectional view) of the attachment-removal mechanism and theadjustment mechanism of the second barrel;

[0038]FIG. 13b is a longitudinal cross-sectional view (YZcross-sectional view) of the third barrel;

[0039]FIG. 14a is a longitudinal cross-sectional view (YZcross-sectional view) of a translating and tilting mechanism;

[0040]FIG. 14b is a plan cross-sectional view (XY cross-sectional view)that shows another example of a tilting mechanism;

[0041]FIG. 15a is an optical path diagram of the projection opticalsystem used in the catadioptric projection exposure apparatus accordingto the fifth mode for carrying out a present invention;

[0042]FIG. 15b is a plan view (cross-sectional view taken in thedirection of the arrows along the line 15 b-15 b in FIG. 15a) of theexposure region of the projection optical system of FIG. 15a;

[0043]FIG. 16a is an optical path diagram of the projection opticalsystem used in the catadioptric projection exposure apparatus accordingto a sixth mode for carrying out the present invention;

[0044]FIG. 16b is a plan view (cross-sectional view taken in thedirection of the arrows along the line 16 b-16 b in FIG. 6a) of theexposure region of the projection optical system of FIG. 16a;

[0045]FIG. 17 is a schematic diagram of the configuration of the opticalsystem according to the seventh mode for carrying out the presentinvention;

[0046]FIG. 18a is a schematic diagram illustrating the alignment methodaccording to a seventh mode for carrying out the present invention;

[0047]FIG. 18b is a view that shows the internal construction of theinterferometer 121 of FIG. 18a;

[0048]FIG. 19a is a diagram illustrating the positioning of the foldingmirrors and reflecting surface with respect to the support body of theoptical system of FIG. 17;

[0049]FIG. 19b is a diagram illustrating the positioning of thereflecting surface with respect to the axis of first lens barrel of theoptical system of FIG. 17; and

[0050]FIG. 20 is a flowchart setting forth the steps for carrying out adevice manufacturing method according to one mode of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0051] The present invention relates to a projection exposure apparatusand method used when transferring a projection master plate (mask,reticle and the like) onto a substrate in photolithographic processesfor manufacturing devices like semiconductor devices, image pickupdevices, liquid crystal display devices and thin film magnetic heads,and further relates to an optical system having a folding member suitedto the projection exposure apparatus, and a method for manufacturingoptical system.

[0052] The following explains the projection exposure apparatus providedwith a catadioptric optical system according to the present invention,based on the drawings. FIG. 1a is a schematic of the projection exposureapparatus 10 according to the first and second modes for carrying outthe present invention. An XYZ coordinate system is employed, as shown.

[0053] In apparatus 10, reticle R, as the projection master platewhereon a predetermined circuit pattern is formed, is arranged in anobject plane OP of a catadioptric optical system C. A wafer W(substrate), serving as a workpiece having a coating of a photosensitivematerial like photoresist, is arranged in an image plane IP ofcatadioptric optical system C. Reticle R is held by a reticle stage RSso that the normal line of the patterned surface is in the direction ofgravity (the Z direction in FIG. 1a). Wafer W is held by a wafer stageWS so that the normal line of that surface is substantially parallel tothe direction of gravity (Z direction). Reticle stage RS is constructedso that it is moveable along the ±Y direction for the purpose ofscanning and exposure. In addition, wafer stage WS is constructed sothat it is moveable in the XY plane, and so that the position in the Zdirection and the tilt in the Z direction of wafer W are adjustable.

[0054] An illumination optical apparatus IS is arranged above reticle R(on the −Z direction side) to evenly illuminate a slit-shaped(rectangular or oblong) illumination region on reticle R. In the presentexample, the length direction of the slit-shaped illumination region isset to the X direction in the Figure. Furthermore, instead of aslit-shaped illumination region, an annular illumination region may alsobe used.

[0055] Catadioptric optical system C further includes first and secondimaging optical systems A and B, respectively, and an aperture stop ASwith a variable aperture diameter, located at the pupil positionthereof. System C is substantially telecentric on the reticle R side andthe wafer W side. Furthermore, a pupil filter such as disclosed in, forexample, Japanese Patent

[0056] Application Kokai No. Hei 6-349698 and the like, may also bearranged at the position of aperture stop AS.

[0057] Illumination optical apparatus IS comprises an exposure lightsource (not shown) comprising an ArF excimer laser light source, anoptical integrator (not shown) to make the illumination intensitydistribution of the exposure light having a wavelength of 193.3 nm fromthis light source uniform, an illumination system aperture stop, avariable field stop (reticle blind) (not shown) and a condenser lenssystem (not shown), and the like. Furthermore, a 248 nm wavelength KrFexcimer laser light, a 157 nm wavelength F₂ laser light, the higherharmonics of a YAG laser, or a mercury lamp that supplies ultravioletlight below 300 nm may also be used as the exposure light source.

[0058] With continuing reference to FIG. 1a, illumination light IL issupplied by illumination optical apparatus IS and proceeds along the +Zdirection, and illuminates reticle R. The light from reticle R enterscatadioptric-type first imaging optical system A wherein a concavereflecting mirror MC and a plurality of dioptric optical members(lenses) L1-L3 are arranged along optical axis Z1. System A forms anintermediate image (not shown) of the pattern on the exposure region onreticle R on the exit side of first imaging optical system A. The lightemerging from first imaging optical system A travels substantially alongthe −Z direction, is reflected by a plane mirror M1 as a first foldingmember, and proceeds to a plane mirror M2 as a second folding membersubstantially along the +Y direction (along optical axis Z2) after thedirection of travel thereof is folded substantially by 90°. The lightreflected by mirror M2 travels substantially along the +Z directionafter the direction of travel thereof is folded substantially by 90°,and then enters dioptric-type second imaging optical system B comprisingdioptric optical members L4 and L5 arranged along optical axis Z3parallel to optical axis Z1. The image of the light source ofillumination optical apparatus IS is formed at the pupil position(position of aperture stop AS) of catadioptric optical system C. Inother words, reticle R is Köhler illuminated. Then, the image of thepattern of Köhler illuminated reticle R is reduced via catadioptricoptical system C by projection magnification β(|β| is ¼ in the presentexample, but may be another projection magnification like {fraction(1/5, 1/6)} and the like), and is formed in image plane (second surface)IP of catadioptric optical system C.

[0059]FIG. 1b shows the exposure region EA in image plane IP.Catadioptric optical system C in the present example isaberration-corrected in circular region CA having a radius of 17.1 mmabout optical axis Z3. Slit-shape exposure region EA is 25×6 mm and isset in aberration corrected region CA and outside of shaded region SHAhaving a radius of 5 mm about optical axis Z3. Accordingly, exposureregion EA can be set substantially freely, and may be set, for example,to an arcuate exposure region having the shape of one part of a ring.

[0060] Returning to FIG. 1a, an autofocus/leveling sensor AF fordetecting the position in the Z direction of exposure region EA on waferW and the inclination with respect to the Z direction is provided infront of lens barrel 20 of catadioptric optical system C. A wafer stagecontrol unit (WSCU) in electrical communication with sensor AF and waferstage WS controls the drive of the wafer stage based on the output fromsensor AF. This allows the exposure region EA on wafer W tosubstantially coincide with image plane IP of catadioptric opticalsystem C.

[0061] Before the actual exposure operation, reticle stage RS positionsreticle R in the X direction, Y direction and rotational direction, andwafer stage WS aligns the surface of wafer W with image plane IP ofcatadioptric optical system C and positions wafer W in the X directionand Y direction. Subsequently, the illumination region on reticle R isilluminated by illumination optical apparatus IS while reticle R andwafer W are synchronously scanned along the Y direction with a speedratio corresponding to projection magnification β of the catadioptricoptical system. After exposure of the pattern image of reticle R ontoone exposure region on wafer W is finished, the next exposure region onwafer W is scanned and exposed by stepping wafer stage WS. Theseoperations are repeated by the step-and-scan system. Since this type ofstep-and-scan system should obtain satisfactory imaging performance inthe slit-shaped exposure region, a larger shot region on wafer W can beobtained without increasing the size of catadioptric optical system C.

[0062] In the present example, as shown in FIG. 1a, each of the opticalmembers (lenses L1-L3 and concave reflecting mirror MC) that constitutefirst imaging optical system A are arrayed along optical axis Z1parallel to the direction of gravity. Each of the optical members(lenses L4 and L5 and aperture stop AS) that constitute second imagingoptical system B are arrayed along optical axis Z3 parallel to thedirection of gravity. Lenses are not provided along optical axis Z2 inthe direction that traverses the direction of gravity. Consequently, thegeneration of asymmetric aberrations due to the effect of gravity onthese optical members can be controlled. Furthermore, the lens barrel ofa conventional right cylinder-type catadioptric optical system, which isa field-proven support technology, can be applied as is to the opticalmembers in first imaging optical system A and second imaging opticalsystem B. Accordingly, there are advantages in that the manufacture ofcatadioptric optical system C is easy and the performance stabilityafter installation of the apparatus can be improved. Furthermore, in thepresent invention, the substantial coincidence of the normal lines ofthe reticle R surface and wafer W surface with the direction of gravityincludes the state wherein the normal lines are inclined by a minuteamount to adjust the reticle surface or wafer surface.

[0063] In the above mode for carrying out the present invention, the NAof the light beam passing through first imaging optical system A, whichis a catadioptric optical system, is smaller than that in second imagingoptical system B, which is a dioptric optical system. Accordingly,separation of the optical paths in first imaging optical system A iseasy, and the NA can be made larger than the case wherein the secondimaging optical system is made a catadioptric optical system. Inaddition, a light beam of a small NA passes through first imagingoptical system A. Accordingly, the aperture diameter of concavereflecting mirror MC can be reduced.

[0064] In projection exposure apparatus 10 of the present mode forcarrying out the present invention, one intermediate image is formed inthe optical system, and first folding member M1 is arranged in thevicinity of this intermediate image. Since the diameter of the lightbeam is reduced in the vicinity of the intermediate image, separation ofthe optical paths by first folding member M1 can be realized easily.Only one intermediate image is formed in the optical system of thepresent mode for carrying out the present invention. Thus, the totallength of the optical system can be shortened, as compared to the casewherein a plurality of intermediate images is formed.

[0065] Also, only one concave mirror, and not a plurality thereof, isused in projection exposure apparatus 10. This has the advantage thatthe optical paths can be separated even if exposure region EA is notvery remote from the optical axis, thus not causing an increase in thesize of the optical system.

[0066] Reticle R may be illuminated so that projection optical system(catadioptric optical system) C can form a slit-shaped or arcuateexposure region EA that does not include the optical axis of the secondimaging optical system in the image plane. If reticle stage RS and waferstage WS are scanned, then first folding member M1 that folds the lightpassing through first imaging optical system A toward the second imagingoptical system B can be easily arranged at a position that does notinterfere with the light beam proceeding from the reticle to the concavemirror. Thus, the use of a beam splitter having atransmitting-reflecting surface for optical path separation becomesunnecessary. Consequently, the generation of stray light caused by flareand illumination unevenness can be reduced, and the risk of causingdeterioration in image quality is extremely small.

[0067] Next, a mode for carrying out the present invention will beexplained using numerical values. FIG. 2 and FIG. 5 show optical pathdiagrams of the catadioptric optical system according to the first andsecond modes for carrying out the present invention, respectively. InFIG. 2 and FIG. 5, an XYZ coordinate system, the same as that in FIG.1a, is employed.

[0068] With reference now to FIGS. 2 and 5, a catadioptric opticalsystems C1 and C2 according to first and second modes for carrying outthe present invention is one now set forth. System C1 comprisescatadioptric-type first imaging optical system A, dioptric-type secondimaging optical system B, and plane mirror M1 as the first foldingmember and plane mirror M2 as the second folding member arranged betweenthe first and second imaging optical systems.

[0069] In FIG. 2 and FIG. 5, first imaging optical system A according tothe first and second modes for carrying out the present inventioncomprises 1-1th lens group G11, 1-2th lens group G12 and concavereflecting mirror MC. Lens groups G11, G12 and concave reflecting mirrorMC are arranged coaxially so that the light from the first surface(reticle R) sequentially passes through lens group G11, lens group G12and then reaches concave reflecting mirror MC. The light reflected byconcave reflecting mirror MC emerges from lens group G12. First imagingoptical system A forms an intermediate image of reticle R at a positionseparated from the optical axis in the optical path between lens groupG11 and lens group G12. First imaging optical system A according to thefirst and second modes for carrying out the present invention has slightreduction magnification.

[0070] Second imaging optical system B according to the first and secondmodes for carrying out the present invention comprises a lens group G21having positive refractive power, aperture stop AS and 2-2th lens groupG22 having a positive refractive power. Lens groups G21, G22 andaperture stop AS are arranged coaxially so that the light from theintermediate image passing from plane mirrors M1, M2 sequentially passesthrough lens group G21, aperture stop AS and lens group G22.

[0071] First imaging optical system A is in the optical path betweenreticle R and concave reflecting mirror MC. The pupil plane thereof isat a position remote from concave reflecting mirror MC. The light sourceimage formed by illumination optical system IS is relayed to the pupilplane of first imaging optical system A. However, if a light sourcehaving a high output like a laser light source, for example, is used, aconcentration of energy will occur at the position of the light sourceimage. If the pupil plane thereof coincides with the reflecting surfaceof concave reflecting mirror MC, there is a risk that the reflectivefilm on the reflecting surface will be damaged. Nevertheless, since thelight source image is formed at a position remote from the reflectingsurface of concave reflecting mirror MC, it does not cause damage to thereflective film. The position of the pupil plane is positioned in theoptical path between the reticle and the concave reflecting mirror.Thus, the exit pupil of first imaging optical system A can be set on thesecond imaging optical system B side of the intermediate image. Thereby,it becomes unnecessary to make second imaging optical system Btelecentric on the intermediate image side. In this case, system C1,which has no lens equivalent to a field lens between the first andsecond folding members M1 and M2, has the advantage that the aperturediameter of second imaging optical system B can be reduced.

[0072] In the first mode for carrying out the present invention shown inFIG. 2, lens group G11 in first imaging optical system A comprises twonegative meniscus lenses L111, L112 whose concave surfaces face thereticle R side. These two lenses L111, L112 are both formed of syntheticquartz.

[0073] Lens group G12 in first imaging optical system A comprises, inorder from the reticle R side, a biconvex positive lens L121, a positivemeniscus lens L122 whose convex surface faces the reticle R side, abiconcave negative lens L123, a biconvex positive lens L124, a positivemeniscus lens L125 whose convex surface faces the reticle R side, and anegative meniscus lens L126 whose concave surface faces the reticle Rside. Furthermore, biconvex positive lens L124 is formed of fluorite,and the other lenses L121 to L123, L125 to L126 in lens group G12 areformed of synthetic quartz.

[0074] The reflecting surface of plane mirror M1 has an oblong-shapedeffective region, and is planar over the entire effective region.Furthermore, this reflecting surface is provided between lens group G11and lens group G12 so that the lengthwise direction of the effectiveregion is in the X direction and the widthwise direction is inclined by45° with respect to the Z direction.

[0075] The reflecting surface of plane mirror M2 as the second foldingmember has an approximately elliptical-shaped effective region, and isplanar over the entire effective region. Furthermore, the reflectingsurface of plane mirror M2 is provided so that the minor axis of theelliptical-shaped effective region is in the X direction, and the majoraxis of the elliptical-shaped effective region is inclined by 45° withrespect to the Z direction. In other words, in the present example, thereflecting surface of plane mirror M1 and the reflecting surface ofplane mirror M2 are arranged so that they are mutually orthogonal.

[0076] Lens group G21 in second imaging optical system B comprises, inorder from the plane mirror M2 side (light entrance side), a biconvexpositive lens L211, a negative meniscus lens L212 whose convex surfacefaces the wafer W side, a negative meniscus lens L213 whose concavesurface faces the wafer W side, and a biconvex positive. lens L214.Furthermore, the concave surface on the wafer W side of negativemeniscus lens L213 is aspherical. Biconvex positive lens L214 is formedof fluorite, and the other lenses L211 to L213 in lens group G21 areformed of synthetic quartz.

[0077] Lens group G22 in second imaging optical system B comprises, inorder from the group G21 side (light entrance side), a biconcavenegative lens L221, a biconvex positive lens L222, two positive meniscuslenses L223, L224 whose concave surfaces face the wafer W side, abiconcave negative lens L225, and two biconvex positive lenses L226,L227. Furthermore, the concave surface (*) on the wafer W side ofbiconcave negative lens L225 is aspherical. In addition, all lenses L221to L227 that constitute lens group G22 are formed of synthetic quartz.

[0078] In the second mode for carrying out the present invention shownin FIG. 5, system C2 includes lens group G11 in first imaging opticalsystem A, which comprises, in order from the reticle R side, aplanoconvex negative lens L111 whose planar surface faces the reticle Rside, a negative meniscus lens L112 whose concave surface faces thereticle R side, and a positive meniscus lens L113 whose concave surfacefaces the reticle R side. All lenses L111 to L113 that constitute lensgroup G11 are formed of synthetic quartz.

[0079] Lens group G12 in first imaging optical system A comprises, inorder from the reticle R side, a biconvex positive lens L121, a positivemeniscus lens L122 whose convex surface faces the reticle R side, abiconcave negative lens L123, a biconvex positive lens L124, a positivemeniscus lens L125 whose convex surface faces the reticle R side, and anegative meniscus lens L126 whose concave surface faces the reticle Rside. In lens group G12, biconvex positive lens L124 is formed offluorite, and the other lenses L121 to L123, and L125 to L126 are formedof synthetic quartz.

[0080] The reflecting surface of plane mirror M1 as the first foldingmember has an oblong-shaped effective region, and is planar over theentire effective region. This reflecting surface is provided betweenlens group G11 and lens group G12 so that the lengthwise direction ofthe effective region is in the X direction and the widthwise directionis inclined by 45° with respect to the Z direction.

[0081] The reflecting surface of plane mirror M2 as the second foldingmember has an approximately elliptical-shaped effective region, and isplanar over the entire effective region. The reflecting surface of planemirror M2 is provided so that the minor axis of the elliptical-shapedeffective region is in the X direction, and the major axis of theelliptical-shaped effective region is inclined by 45° with respect tothe Z direction. In other words, in the present example as well, thereflecting surface of plane mirror M1 and the reflecting surface ofplane mirror M2 are arranged so that they are mutually orthogonal.

[0082] Lens group G21 in second imaging optical system B comprises, inorder from the plane mirror M2 side (light entrance side), a biconvexpositive lens L211, a negative meniscus lens L212 whose convex surfacefaces the wafer W side, a negative meniscus lens L213 whose convexsurface faces the wafer W side, and a biconvex positive lens L214. In.lens group G21, biconvex positive lens L214 is formed of fluorite, andthe other lenses L211 to L213 are formed of synthetic quartz. Inaddition, the concave surface (*) on the wafer W side of the negativemeniscus lens L213 is aspherical.

[0083] Lens group G22 in second imaging optical system B comprises, inorder from the lens group G21 side (light entrance side), a negativemeniscus lens L221 whose convex surface faces the wafer W side, apositive meniscus lens L222 whose convex surface faces the wafer W side,a biconvex positive lens L223, a positive meniscus lens L224 whoseconvex surface faces the wafer W side, a biconcave negative lens L225, apositive meniscus lens L226 whose convex surface faces the wafer W side,and a biconvex positive lens L227. Furthermore, the concave surface onthe wafer W side of biconcave negative lens L225 is aspherical surface.In addition, all lenses L221 to L227 that constitute lens group G22 areformed of synthetic quartz.

[0084] As described in the above first and second modes for carrying outthe present invention, by providing second imaging optical system B withlens group G21 having a positive refractive power, aperture stop ASarranged between lens group G21 and the reduced image, and lens groupG22 arranged between aperture stop AS and the reduced image, and byproviding at least one aspherical surface each in lens group G21 andlens group G22, spherical aberration and coma can be satisfactorilycorrected with good balance, and optical performance can be improved.Alternatively, for substantially the same optical performance, a largeexposure region can be achieved without the attendant increase in thesize of the optical system. Furthermore, by making the aperture diameterof aperture stop AS variable, it can be adjusted to the optimalresolving power and depth of focus for the particular exposure pattern.

[0085] First imaging optical system A in the first and second modes forcarrying out the present invention (i.e., systems C1 and C2) forms anintermediate image in the optical path between first folding member M1and first imaging optical system A. Thus, the optical paths can beeasily separated by the first folding member.

[0086] At this point, it is preferable the present invention satisfycondition (1) below, wherein LF1 is the distance between theintermediate image plane and the effective region of the first foldingmember, and S1 is the area of the effective region of the first surface.

LF1/S1>0.002  (1)

[0087] Condition (1) stipulates the appropriate position for planemirror M1. If condition (1) is not satisfied, a deterioration in opticalperformance, such as illumination unevenness due to flaws in thefabrication of the reflecting surface of first folding member M1,defects in the reflective film, and dirt on the reflecting surfacecannot be prevented, and a sufficient resolving power cannot be obtainedover the entire exposure region. Accordingly, it is preferable to set anupper limit value to condition (1) of 4 in order to make separation ofthe optical paths by first folding member M1 easy. In addition, it ispreferable to set the lower limit value to 0.005 in order to improve theability to mass-produce the projection optical system.

[0088] In condition (1), distance LF1 between the intermediate imageplane and first folding member M1 is the distance along a directionparallel to the optical axis between the intermediate image plane andthe position closest to the intermediate image plane in the effectiveregion of first folding member M1.

[0089] In addition, it is preferable in the first and second modes forcarrying out the present invention to satisfy condition (2) below,wherein cl is the maximum effective diameter among the effectivediameters of the optical members that constitute first imaging opticalsystem A, c2 is the maximum effective diameter among the effectivediameters of the optical members that constitute second imaging opticalsystem B, and LO2 is the distance between optical axis Z1 of the firstimaging optical system and optical axis Z3 of the second imaging opticalsystem.

LO 2/(c 1+c 2)>0.7  (2)

[0090] Condition (2) stipulates an appropriate interaxis distancebetween the first and second imaging optical systems. If condition (2)is not satisfied, the spacing to stably hold the optical members thatconstitute these optical systems cannot be ensured, making it difficultto continuously realize sufficient optical performance of the projectionoptical system. To prevent increasing the size of second folding memberM2, it is preferable to set an upper limit value to condition (2) of2.5. In addition, to make adjustment of the optical system easier, it ispreferable to set the lower limit value of condition (2) to 0.9.

[0091] In addition, in the catadioptric optical system according to thefirst and second modes for carrying out the present invention, at leastone positive lens among the dioptric optical members arranged in theround-trip optical path in first imaging optical system A, namely theoptical path from first surface R to concave mirror MC and the opticalpath from concave mirror MC to the intermediate image, is formed offluorite. Chromatic aberration is corrected with a comparatively smallnumber of fluorite lenses by making the chromatic aberration-correctingeffect of the fluorite function in both directions of the round-tripoptical path. In the first and second modes for carrying out the presentinvention, the pupil plane is formed at a position apart from thereflecting surface of concave reflecting mirror MC to prevent damage tothe reflective film. Thus, the direction of fluctuations in opticalperformance of the first imaging optical system due to fluctuations inenvironmental factors like temperature varies with the positionalrelationship between the pupil plane and concave reflecting mirror MC.In other words, the state of the light beam that passes through thepositive lens made of fluorite in first imaging optical system A losessymmetry between the going path (optical path from first surface R toconcave reflecting mirror MC) and the returning path (optical path fromconcave reflecting mirror MC to the intermediate image). The directionof fluctuations in the optical performance varies depending on whetherthe pupil plane is positioned in the going path or returning path.Volumetric changes due to changes in the temperature of the fluoritecause expansion proportional to the change in temperature. Thus, theradius of curvature of the lens increases as the temperature rises. Inaddition, since changes in the refractive index due to changes in thetemperature of the fluorite are inversely proportional to the change intemperature, the refractive index decreases as the temperatureincreases. Since both of the above cases work to lower the refractivepower of the surface, the focal length of a fluorite lens increases asthe temperature of the lens rises.

[0092] If the pupil plane of first imaging optical system A ispositioned between first surface R and concave reflecting mirror MC, asin the first and second modes for carrying out the present invention,fluctuations in optical performance due to changes in the temperature ofthe positive lenses made of fluorite in first imaging optical system Ahave a stronger effect in the going path. Accordingly, in the first andsecond modes for carrying out the present invention, fluctuations inoptical performance are generated in the direction the reverse of thatin the first imaging optical system and the total amount of fluctuationin the optical system is reduced by arranging the positive lens made offluorite in lens group G21 on the intermediate image side of the pupilplane of second imaging optical system B.

[0093] If the pupil plane of first imaging optical system A is arrangedbetween concave reflecting mirror MC and the intermediate image,fluctuations in optical performance due to changes in the temperature ofthe positive lens made of fluorite in first imaging optical system Ahave a stronger effect in the returning path. In this case, by arrangingthe positive lens made of fluorite in lens group G22 on the secondaryimage side of the pupil plane of second imaging optical system B,fluctuations in optical performance in the direction the reverse of thatin the first imaging optical system can be generated, and the totalamount of fluctuation in the optical system can be reduced.

[0094] The abovementioned fluctuations in optical performance caused bytemperature changes are fluctuations principally in the direction of theimage height as represented by fluctuations in magnification, and do notinclude fluctuations in the direction of the optical axis as representedby fluctuations in focus. Nevertheless, since fluctuations in thedirection of the optical axis can be easily corrected by autofocusmechanisms and the like, this is actually a small problem for projectionexposure. Furthermore, to reduce fluctuations in both the image heightdirection and in the optical axis direction, we can consider the use offluorite in the negative lens on the second surface side of the pupilplane of second imaging optical system B. However, this cannot lead to arealistic solution because the efficiency of chromatic aberrationcorrection is poor in the initial state (i.e., the state whereinenvironmental optical performance fluctuations are not generated).

[0095] It is preferable in the first and second modes for carrying outthe present invention that the catadioptric optical system be an opticalsystem telecentric on the first and second surface sides.

[0096] It is also preferable that systems C1 and C2 satisfy condition(3) below, wherein LP3 is the distance between the pupil plane of firstimaging optical system A and concave reflecting mirror MC, and D1 is theeffective radius of concave reflecting mirror MC.

2.50>LP 3/D 1>0.15  (3)

[0097] Condition (3) stipulates an appropriate distance between thepupil plane and the concave reflecting mirror to achieve satisfactorycorrection of chromatic aberration while avoiding damage to thereflective film by the laser, and to make the optical axes of alloptical members that constitute the catadioptric optical system mutuallyparallel. If L3/D1 exceeds the upper limit in condition (3), thecorrection of high-order chromatic aberrations like transverse chromaticbecomes difficult. In addition, if LP3/D1 falls below the lower limit incondition (3), damage to the reflective film by the laser cannot beavoided, and it is also difficult to make the optical axes of all lensesparallel.

[0098] If the pupil plane of first imaging optical system A ispositioned between the first surface and the concave reflecting mirror,and at least one positive lens made of fluorite is arranged in lensgroup G21 on the intermediate image side of the pupil plane of secondimaging optical system B, then it is preferable to satisfy condition (4)below, wherein f12 is the sum of the focal lengths of the positivelenses made of fluorite in lens group G12, and f21 is the sum of thefocal lengths of the positive lenses made of fluorite in 2-1th lensgroup G21.

2.0>f 12/f 21>0.5  (4)

[0099] Condition (4) stipulates an appropriate range for the focallengths of the positive lenses made of fluorite, to reduce fluctuationsin optical performance when the environment changes. If f12/21 exceedsthe upper limit or falls below the lower limit in condition (4),fluctuations in optical performance due to changes in environmentalfactors, particularly temperature, become excessively large, and asufficient resolving power can no longer be continuously maintained.Furthermore, if two or more positive lenses made of fluorite arearranged in lens group G12 or lens group G21, each of the sums of thefocal lengths of the positive lenses made of fluorite should beconsidered.

[0100] The Tables below list the values of the specifications of systemsC1 and C2 of the first and second modes for carrying out the presentinvention. Table 1 and Table 3 include the lens data of the catadioptricoptical systems according to the first and second modes for carrying outthe present invention, respectively. In Table 1 and Table 3, theleftmost column (first column) S indicates the surface number of eachoptical surface (lens surface and reflecting surface), the next columnto the right (second column) R indicates the radius of curvature of eachoptical surface, the next column to the right (third column) d indicatesthe surface spacing between each optical surface, the next column to theright (fourth column) Re indicates the effective radius of each opticalsurface, and the next column to the right (fifth column) “material”indicates the name of the material of which the optical member is made.In addition, in Table 1 and Table 3, d0 is the distance from the objectplane (reticle surface) to the optical surface most reticle-wise, WD isthe distance from the most wafer-wise optical surface to the wafersurface (image plane), β is the lateral magnification of the projectionsystem when light enters the projection system from the reticle side,and NA is the numerical aperture on the wafer side. Furthermore, inTable 1 and Table 3, the sign of the radius of curvature and surfacespacing reverses around a reflecting surface.

[0101] In addition, in Table 1 and Table 3, an asterisk (*) appended toa surface number, indicates an aspherical surface, and the radius ofcurvature for such aspherical surfaces indicates the vertex radius ofcurvature. This aspherical surface shape is represented by condition (a)below. For a tangential plane at the apex of the aspherical surface, theorigin is the position that the optical axis passes through at thetangential plane, and z(y) is based on the vertex of the asphericalsurface, the displacement in the direction of the optical axis of theaspherical surface at the position of height y in the tangential planewhen the direction of travel of the ray is positive. $\begin{matrix}{{x(y)} = {\frac{y^{2}/r}{1 + \sqrt{1 - {\left( {1 + \kappa} \right)\frac{y^{2}}{r^{2}}}}} + {Ay}^{4} + {By}^{6} + {Cy}^{8} + {Dy}^{10} + {Ey}^{12} + {Fy}^{14}}} & (a)\end{matrix}$

[0102] In formula (a), r is the vertex radius of curvature, κ is theconical coefficient, and A, B, C, D, E, F are the aspherical surfacecoefficients. Table 2 and Table 4 list conical coefficient K andaspherical coefficients A, B, C, D, E, F as the aspherical surface datain the first and second modes for carrying out the present invention.

[0103] Furthermore, in the first and second modes for carrying out thepresent invention, the dioptric optical members are formed of syntheticquartz (SiO₂) or fluorite (CaF₂). The refractive index n at the workingreference wavelength (193.3 nm) and the inverse ν of the dispersionvalue at the reference wavelength ±1 pm thereof are as follows.

[0104] Synthetic quartz: n=1.56033 v=1762×10²

[0105] Fluorite: n=1.50146 v=2558×10²

[0106] The dispersion value 1/ν is represented by condition (b) below,wherein the refractive index at the working reference wavelength isn(o), the refractive index at the reference wavelength ±1 pm is n(L),and the refractive index at the working wavelength −1 pm is n(S).

1/v=[n(o)−1]/[n(S)−n(L)]  (b)

[0107] In the fourth column that indicates the effective radius of eachoptical surface, the length of the long side and short side is indicatedfor plane mirror M1, which has an oblong effective region, and thelength of the major axis and minor axis of the ellipse is indicated forplane mirror M2, which has an elliptical effective region. TABLE 1 LENSDESIGN DATA, FIRST MODE d0 = 66.2181 WD = 12.0000 |β| = ¼ NA = 0.75 S Rd Re Material 1 −173.2198 59.9763 77.54 Synthetic Quartz L111 2−199.3558 2.4684 93.84 3 −1413.5392 42.7237 97.79 Synthetic Quartz L1124 −60064.7315 87.0000 104.07 5 1092.1574 26.0439 124.31 Synthetic QuartzL121 6 −832.9175 3.1990 125.18 7 245.6137 35.000 128.10 Synthetic QuartzL122 8 565.3602 304.9236 125.79 9 −220.6579 20.4061 85.82 SyntheticQuartz L123 10 391.9184 5.7049 88.75 11 594.4147 29.9442 89.29 FluoriteL124 12 −412.6301 72.7628 90.63 13 410.4514 26.1344 94.43 SyntheticQuartz L125 14 669.5983 138.8597 93.16 15 −238.4760 25.0000 113.89Synthetic Quartz L126 16 −837.0357 16.6526 129.65 17 −356.5760 −16.6526130.61 Concave Reflect- ing mirror MC 18 −837.0357 −25.0000 129.99Synthetic Quartz L126 19 −238.4760 −138.8597 118.38 20 669.5983 −26.1344110.10 Synthetic Quartz L125 21 410.4514 −72.7628 110.23 22 −412.6301−29.9442 95.29 Fluorite L124 23 594.4147 −5.7049 93.24 24 391.9484−20.4061 92.49 Synthetic Quartz L123 25 −220.6579 −304.9236 86.06 26565.3602 −35.0000 94.14 Synthetic Quartz L122 27 245.6137 −3.1990 95.9828 −832.9175 −26.0439 92.73 Synthetic Quartz L121 29 1092.1574 −1.000090.76 30 ∞ 530.0000 134 × 53 Plane Mirror M1 (oblong) 31 ∞ −129.6727 260× 220 Plane Mirror M2 (ellipse) 32 −416.5064 −43.6858 130.51 SyntheticQuartz L211 33 1614.8553 −19.8749 129.15 34 375.6187 −40.1637 128.76Synthetic Quartz L212 35 992.3735 −154.0322 130.25 36 −540.0532 −30.6056124.67 Synthetic Quartz L213 37* −280.2053 −4.7489 119.84 38 −269.7063−59.8107 120.36 Fluorite L214 39 1000.1381 −18.8527 118.99 40 ∞ −20.0376114.42 Aperture Stop AS (variable) 41 638.2931 −25.0000 113.74 SyntheticQuartz L221 42 −6260.2239 −10.3928 116.87 43 −337.6474 −45.2717 122.52Synthetic Quartz L222 44 2063.2498 −33.0583 121.91 45 −239.6600 −45.1169116.23 Synthetic Quartz L223 46 −4631.0389 −1.0027 112.20 47 −167.6364−40.2179 99.72 Synthetic Quartz L224 48 −1732.6245 −6.1992 94.74 492730.6200 −25.0000 92.94 Synthetic Quartz L225 50* −306.7043 −1.866775.85 51 −254.0551 −24.4188 74.92 Synthetic Quartz L226 52 4420.0238−1.2986 69.49 53 −316.0614 −65.0000 62.88 Synthetic Quartz L227 5412272.4820 (WD) 30.79

[0108] TABLE 2 ASPHERICAL DATA OF THE FIRST MODE FOR CARRYING OUT THEPRESENT INVENTION 37^(th) Surface κ =   0.0000 A = −1.3249 × 10⁻⁰⁸ B =−1.2617 × 10⁻¹³ C =   1.4089 × 10⁻¹⁸ D = −6.4967 × 10⁻²³ E =   3.4235 ×10⁻²⁷ F = −1.5167 × 10⁻³¹ 50^(th) Surface κ =   0.0000 A = −5.0678 ×10⁻⁰⁸ B = −3.8316 × 10⁻¹³ C = −5.6799 × 10⁻¹⁷ D = −6.9166 × 10⁻²² E =  0.0000 F =   0.0000

[0109] TABLE 3 SECOND MODE FOR CARRYING OUT THE PRESENT INVENTION d0 =50.0980 WD = 12.3836 |β| = ¼ NA = 0.75 S R d Re Material 1 ∞ 30.876977.96 Synthetic Quartz L111 2 1358.1393 25.6596 82.00 3 −173.936629.5956 82.54 Synthetic Quartz L112 4 −262.5027 3.9549 93.62 5 −243.758532.1846 94.30 Synthetic Quartz L113 6 −198.6141 78.6305 102.23 7705.6754 29.6916 128.29 Synthetic Quartz L121 8 −853.6854 7.1157 128.859 243.8837 35.0000 130.00 Synthetic Quartz L122 10 393.9524 334.9670126.27 11 −228.4608 20.5261 87.25 Synthetic Quartz L123 12 324.67677.3561 90.62 13 359.7325 40.5663 92.51 Fluorite L124 14 −554.295258.0131 94.34 15 588.9791 33.3872 97.95 Synthetic Quartz L125 163573.1266 113.1955 97.48 17 −249.4612 25.0000 111.74 Synthetic QuartzL126 18 −1326.9703 25.8354 126.13 19 −367.4917 −25.8354 129.94 ConcaveReflect- ing Mirror MC 20 −1326.9703 −25.0000 127.54 Synthetic QuartzL126 21 −249.4612 −113.1955 117.01 22 3573.1266 −33.3872 112.48Synthetic Quartz L125 23 588.9791 −58.0131 111.89 24 −554.2952 −40.5663100.25 Fluorite L124 25 359.7325 −7.3561 97.36 26 324.6767 −20.526194.44 Synthetic Quartz L123 27 −228.4608 −334.9670 87.51 28 393.9524−35.0000 93.84 Synthetic Quartz L122 29 243.8837 −7.1157 96.50 30−853.6854 −29.6916 93.81 Synthetic Quartz L121 31 705.6754 −1.6203 92.0932 ∞ 530.0000 135 × 53 Plane Mirror M1 (oblong) 33 ∞ −100.0000 260 × 220Plane Mirror M2 (ellipse) 34 −473.4614 −50.8662 130.00 Synthetic QuartzL211 35 1218.5628 −18.9785 128.42 36 357.1688 −31.0635 128.11 SyntheticQuartz L212 37 818.7536 −209.4034 129.93 38 −571.9096 −31.2079 123.89Synthetic Quartz L213 39* −295.8211 −4.7127 119.48 40 −291.2028 −53.9868119.84 Fluorite L214 41 858.6769 −19.1416 119.00 42 ∞ −24.0577 115.27Aperture Stop AS 43 719.7751 −25.0000 113.83 Synthetic Quartz L221 446715.0030 −22.3498 117.19 45 −314.9647 −45.0000 124.79 Synthetic QuartzL222 46 −5036.3103 −16.5385 123.55 47 −265.1907 −45.0000 120.07Synthetic Quartz L223 48 9375.9412 −1.1109 116.54 49 −177.9561 −50.1531103.37 Synthetic Quartz L224 50 −18823.9455 −4.9217 94.91 51 1624.4953−25.0000 93.03 Synthetic Quartz L225 52* −247.3912 −1.0000 74.54 53−210.5206 −24.3364 73.99 Synthetic Quartz L226 54 −35247.2125 −1.062169.21 55 −293.7588 −65.0000 63.01 Synthetic Quartz L227 56 56893.1197(WD) 31.15

[0110] TABLE 4 ASPHERICAL DATA OF THE SECOND MODE FOR CARRYING OUT THEPRESENT INVENTION 39^(th) Surface κ =   0.0000 A = −1.3500 × 10⁻⁰⁸ B =−1.2494 × 10⁻¹³ C = −1.3519 × 10⁻¹⁸ D = −9.1832 × 10⁻²³ E =   3.6355 ×10⁻²⁷ F = −1.6744 × 10⁻³¹ 52^(nd) Surface κ =   0.0000 A = −4.8204 ×10⁻⁰⁸ B = −1.1379 × 10⁻¹² C = −6.8704 × 10⁻¹⁷ D = −2.8172 × 10⁻²¹ E =  0.0000 F =   0.0000

[0111] Table 5 below lists the numerical values corresponding to theconditions of the first and second modes for carrying out the presentinvention. TABLE 5 NUMERICAL VALUES CORRESPONDING TO CONDITIONS OF THEFIRST MODE FOR CARRYING OUT THE PRESENT INVENTION L1 = 11.55 S1 = 2400L2 = 530 C1 = 261.22 C2 = 259.88 L3 = 118.11 D1 = 130.61 f12 = 490.57f22 = 430.38 (1) L12/S1 = 0.0556 (2) L2/(c1 + c2) = 1.0171 (3) L3/D1 =0.904 (4) f12/f21 = 1.0171 NUMERICAL VALUES CORRESPONDING TO CONDITIONSOF THE SECOND MODE FOR CARRYING OUT THE PRESENT INVENTION L1 = 6.07 S1 =2400 L2 = 530 C1 = 261.02 C2 = 261.22 L3 = 100.93 D1 = 129.99 f12 =441.59 f22 = 440.56 (1) L12/S1 = 0.0154 (2) L2/(c1 + c2) = 1.0149 (3)L3/D1 = 0.776 (4) f12/f21 = 1.002

[0112]FIG. 3a shows the amount of displacement (deviation) from anapproximate spherical surface of the rotationally symmetric asphericalsurface formed on the concave surface on the wafer side of negativemeniscus lens L213 in catadioptric optical system C of the first modefor carrying out the present invention. FIG. 3b shows the amount ofdisplacement (deviation) from an approximate spherical surface of therotationally symmetric aspherical surface formed on the concave surfaceon the wafer side of biconcave negative lens L225 in the catadioptricoptical system C1 of the first mode for carrying out the presentinvention. In addition, FIG. 6a shows the amount of displacement(deviation) from an approximate spherical surface of the rotationallysymmetric aspherical surface formed on the concave surface on the waferside of negative meniscus lens L213 in the catadioptric optical systemC2 of the second mode for carrying out the present invention. FIG. 6bshows the amount of displacement (deviation) from an approximatespherical surface of the rotationally symmetric aspherical surfaceformed on the concave surface on the wafer side of biconcave negativelens L225 in the catadioptric optical system C2 of the second mode forcarrying out the present invention. In each graph, the abscissa is thedistance of the aspherical surface from the optical axis, and theordinate is the amount of displacement along the optical axis directionfrom the approximate spherical surface (spherical surface having avertex radius of curvature).

[0113] As can be seen from FIG. 3a, FIG. 3b, FIG. 6a and FIG. 6b, amongthe aspherical surfaces that second imaging optical system B possessesin catadioptric optical systems C1 and C2 of the first and second modesfor carrying out the present invention, the cross-sectional shape thatincludes the optical axis of the rotationally symmetric asphericalsurface having a paraxial negative refractive power is a shape havingfirst and second inflection points facing from the optical axis towardthe lens periphery with respect to the approximate spherical surface.The first inflection point is on the optical axis, and thecross-sectional shape from the optical axis to the second inflectionpoint has less curvature than the curvature of an approximate sphericalsurface. The cross-sectional shape from the second inflection point tothe lens periphery has greater curvature than the curvature of anapproximate spherical surface.

[0114]FIGS. 4a-4 f and FIGS. 7a-7 f are plots of the lateral aberrationon wafer W of catadioptric optical systems C1 and C2 respectively. Ineach lateral aberration plot, the solid line represents the aberrationcurve at wavelength λ of 193.3 nm, the broken line represents theaberration curve at wavelength λ of 193.3 nm +1 pm, and the chain linerepresents the aberration curve at wavelength λ of 193.3 nm −1 pm.

[0115] As can be seen from each aberration plot, the catadioptricoptical systems C1 and C2 according to the first and second modes forcarrying out the present invention achieve satisfactory aberrationcorrection in a large exposure region. Accordingly, by incorporatingcatadioptric optical systems C1 and C2 into the projection exposureapparatus shown in FIG. 1, for example, extremely fine patterns can betransferred onto the wafer.

[0116] The pupil plane of first imaging optical system A in systems C1and C2 in the abovementioned modes for carrying out the presentinvention is positioned between concave reflecting mirror MC and firstfolding member M1. Thus, only positive lens L124 in lens group G12 andpositive lens L214 in lens group G21 are formed of fluorite, and allother lenses are formed of synthetic quartz. By this construction,fluctuations in the image height direction in the optical performance inthe image plane of catadioptric optical systems C1 and C2 can beignored, for practical purposes, even if environmental factors, such astemperature, fluctuate. Furthermore, the fluorite lens in lens group G12is not limited to positive lens L124, and other positive lenses, whosenumber is not limited to one, may also be formed of fluorite. Inaddition, the fluorite lenses in lens group G21 are also not limited topositive lens L214, and other lenses, whose number is not limited toone, may also be formed of fluorite. The pupil plane of first imagingoptical system A is preferably positioned between the first surface(reticle R) and concave reflecting mirror MC. Accordingly, all lensesthat constitute lens group G21 may be formed of synthetic quartz, and atleast any one positive lens among the positive lenses in lens group G22may be formed of fluorite. By this construction, fluctuations in theimage height direction in the optical performance in the image plane ofcatadioptric optical systems C1 and C2 can be ignored, for practicalpurposes, even if environmental factors, such as temperature, fluctuate.

[0117] In systems C1 and C2, the two lens surfaces having negativerefractive power that interpose aperture stop AS are asphericalsurfaces. However, to further improve optical performance or to realizegreater compactness and a reduction in the number of lenses, two or morelens surfaces may be formed in an aspherical surface shape.

[0118] Also, in systems C1 and C2, the imaging performance can bemicroadjusted by adjusting, for a lens of at least any one lens groupamong lens group G1, lens group G12, lens group G21 and lens group G22,the position in the optical axis direction, the position in a directionorthogonal to the optical axis, the position in the rotational directionabout the optical axis, or the position in the rotational direction withthe direction orthogonal to the optical axis as the axis.

[0119] Also, the atmosphere in lens barrel 20 of catadioptric opticalsystem C of FIG. 1 may be replaced with a gas other than air (forexample, nitrogen, helium and the like).

[0120] Next, the third mode for carrying out the present invention willbe explained with reference to FIG. 8 and FIG. 11 apparatus 200. FIG. 8is a cross-sectional view that shows the support structure of thecatadioptric-type projection optical system used in the projectionexposure apparatus of the third mode for carrying out the presentinvention. Furthermore, since projection optical system C2 is used inthe projection exposure apparatus according to the third mode forcarrying out the present invention as set forth in Table 3 and Table 4above, a detailed explanation thereof is omitted.

[0121] In apparatus 200 of FIG. 8, first imaging optical system A thatforms an intermediate image of object plane R (mask surface) is housedin first lens barrel 201, and second imaging optical system B thatreimages this intermediate image (secondary image) in the image plane(wafer W surface) is housed in third lens barrel 203.

[0122] First and second plane mirrors M1, M2 serving as folding membersfor guiding the light from first imaging optical system A to the secondimaging optical system B are housed in second lens barrel 202. Therein,the optical axis (first optical axis Z1) of the first imaging opticalsystem is arranged in the vertical Z direction. Furthermore, first planemirror M1 arranged in the vicinity of the position at which theintermediate image is formed folds first optical axis Z1 of the firstimaging optical system by 90° and transforms it to second optical axisZ2 extending horizontally in the Y direction. Second plane mirror M2 isarranged along second optical axis Z2, and second optical axis Z2 isfurther folded 90° by plane mirror M2 and transformed to third opticalaxis Z3 extending in the vertical Z direction. Plane mirrors M1, M2 aremutually orthogonal and are held by second lens barrel 202 so that theyboth form an angle of 45° with respect to second optical axis Z2.

[0123] The support structure for supporting projection optical system C2as part of apparatus 200 is now explained, referring to FIGS. 9a-9 c,which are oblique views that shows lens barrels 201-203. First lensbarrel 201 holds first imaging optical system A and third lens barrel203 holds the second imaging optical system. These lens barrels areformed substantially as cylinders. Second lens barrel 202 that holdsplane mirrors M1, M2 is formed substantially as a truncated pyramid.Furthermore, first lens barrel 201 is provided with opening 201 b, andpart of second lens barrel 202 enters into opening 201 b when assemblingthe projection optical system.

[0124]FIG. 10 is an oblique view of the frame structure that supportslens barrels 201-203. In FIG. 10, lower frame 205 is formed as a plateand is provided with openings 205 a, 205 b through which first lensbarrel 201 and third lens barrel 203 pass. Among these openings, at theperimeter of opening 205 a for the first lens barrel is provided in astanding state four main supports 206 a to 206 d, and upper frame 207 isaffixed to the top surfaces of main supports 206 a to 206 d. Upper frame207 is provided with U-shaped opening 207 a that supports first lensbarrel 201.

[0125] The upper part of first lens barrel 201 is provided with flange201 a that protrudes sideways. First lens barrel 201 is supported bymounting the bottom surface of flange 201 a onto the peripheral topsurface of U-shaped opening 207 a of upper frame 201. Likewise, thelower part of third lens barrel 203 is provided with flange 203 a thatprotrudes sideways. Third lens barrel 203 is supported by mounting thebottom surface of flange 203 a onto the peripheral top surface ofopening 205 b, for the third lens barrel, of lower frame 205.

[0126] On the other hand, a pair of auxiliary supports 208 a, 208 b isformed in an inverted L shape and are affixed midway between first lensbarrel opening 205 a and third lens barrel opening 205 b of lower frame205. Second lens barrel 202 is supported by these auxiliary supports 208a, 208 b.

[0127] The frame of the exposure apparatus of the present workingexample as described above comprises lower frame 205, main supports 206a to 206 d, upper frame 207 and auxiliary supports 208 a, 208 b, andeach of the lens barrels 201, 202, 203 are supported mutuallyindependently by the frame.

[0128] Next, first lens barrel 201 is supported by the bottom surface offlange 201 a provided on first lens barrel 201. The bottom surface offlange 201 a is located at a position wherein the spacing between thepattern surface of the reticle (object plane R) to the intermediateimage is internally divided by a ratio of 1:(−βA). Here, βA is theimaging magnification of first imaging optical system A. Imagingmagnification βA of first imaging optical system A according to thepresent working example shown in Table 1 and Table 2 above issubstantially −1.25. Accordingly, as shown in FIG. 8, the bottom surfaceof flange 201 a of first lens barrel 201 is located substantially at themidpoint of the distance from the reticle (object plane R) to theintermediate image, namely at a position 106 mm below object plane OP(horizontal plane through which point PA shown in FIG. 8 passes).

[0129] Third lens barrel 203 is supported by the bottom surface offlange 203 a provided on third lens barrel 203. The bottom surface offlange 203 a is located at a position wherein the spacing from theintermediate image to the photosensitive surface of the wafer (imageplane W) is internally divided by a ratio of 1:(−βB). Therein, βB is theimaging magnification of second imaging optical system B. Imagingmagnification βB of second imaging optical system B according to thepresent working example shown in Table 1 and Table 2 above issubstantially −0.20. Accordingly, as shown in FIG. 8, the bottom surfaceof flange 203 a of third lens barrel 203 is located at the point whereinthe distance from the intermediate image to image plane W is internallydivided by a ratio of 1:0.20, namely at a position at a distance of 232mm measured along the optical-axis upward from image plane IP(horizontal plane through which point PB shown in FIG. 8 passes).

[0130] The operation of this construction is now briefly explained,referring to FIG. 11. If h0 is the object height for an arbitraryimaging optical system, y0 is the image height and β is the lateralmagnification, then:

β=y 0/h 0  (c)

[0131] Therein, the height of the object and the image are measured inthe same direction. Accordingly, h0<0 and y0>0 in the example shown inFIG. 11. In addition, since the specific configuration and arrangementposition of the imaging optical system does not present a problem, onlyoptical axis z0 of the imaging optical system is shown in FIG. 11.

[0132] If the imaging optical system is rotated by just microangle θ inthe counterclockwise direction about point P on optical axis z0, theoptical axis after rotation changes to Z1. Even if a light beam passesthrough a single lens two times as in a catadioptric system, objectheight h1 and image height y1 after rotation are as follows, wherein theaxial distance measured from the object point to the image point ispositive, the axial distance from the object point to center of rotationP is a, and the axial distance from the center of rotation P to theimage point is b.

h 1=h 0+aθ  (d)

y 1=y 0−bθ  (e)

[0133] If the following relationship between object height h1 and imageheight y1 after rotation holds, then the image point does not deviateeven after rotation of the imaging optical system.

y 1/h 1=β  (f)

[0134] The following condition is obtained based on conditions (c) to(f):

a:b=1:(−β)  (g)

[0135] In other words, it can be seen that it is preferable to supportthe imaging optical system at point P, since the image point does notdeviate even if the imaging optical system is rotated about a point(external dividing point when β is positive) wherein the object-imagedistance is internally divided by a ratio of 1:(−β).

[0136] The following explains the effect of the present working example.The degrees of freedom for a position that can be obtained in athree-dimensional object are the six degrees of freedom of the positionsin the X, Y and Z directions and the angular positions about the X, Yand Z axes. Since first lens barrel 201 and third lens barrel 203 areseparately supported by a frame at the bottom surfaces of flanges 201 a,203 a, parallel movement in the vertical Z direction, parallel movementin the horizontal X and Y directions, and rotation about the vertical Zaxis are difficult to produce. In particular, the vertical Z axis is inthe direction of optical axes Z1, Z3, and both first imaging opticalsystem A and second imaging optical system B are formed symmetricallyabout optical axes Z1, Z3. Thus, no aberrations whatsoever are generatedeven if rotation about the vertical Z axis is produced.

[0137] Based on the above, the only motion that can be produced in firstlens barrel 201 and third lens barrel 203 is rotational motion about thehorizontal X and Y axes. Moreover, first lens barrel 201 is supported bya plane surface, wherein the object-image distance of first imagingoptical system A supported by first lens barrel 201 is internallydivided by a ratio of 1:(−βA). Third lens barrel 203 is also supportedby a plane surface, wherein the object-image distance of second imagingoptical system B to be supported by third lens barrel 203 is internallydivided by a ratio of 1:(−βB). Consequently, the amount of imagedeviation produced is small, even if first lens barrel 201 or third lensbarrel 203 is rotated about the horizontal X and Y axes.

[0138] In addition, image deviation caused by first lens barrel 201 andthird lens barrel 203 is difficult to produce. Thus, it is clear that,if image deviation is produced, the cause thereof is due to one of thewafer stage, the reticle stage or second lens barrel 202. In otherwords, specification of the cause of image deviation is simplified.

[0139] Next, although parallel movement of second lens barrel 202 in thevertical Z direction and parallel movement in the horizontal X and Ydirections are difficult to produce, there is a risk of rotation aboutthe X, Y and Z axes. If any one of these occurs, image deviation will beproduced. However, even if first lens barrel 201 or third lens barrel203 vibrates, that vibration is not transmitted and does not vibratesecond lens barrel 202, since second lens barrel 202 is directly held bythe frame. Accordingly, if the stability of the frame is increased, thevibration of second lens barrel 202 can be sufficiently prevented.

[0140] The configuration of the present working example is effectiveeven when assembling the projection optical system. To assembleprojection optical system C2, as shown in FIG. 8, lens barrels 201 to203 are first assembled. At this point, lens barrels 201 to 203 are easyto assemble, since they have a single optical axis. Among these, firstlens barrel 201 and third lens barrel 203 should be stacked so thatoptical axes Z1, Z3 do not deviate from the optical members below. Inaddition, second lens barrel 202 should be assembled so that planemirrors M1, M2 form a right angle.

[0141] Next, to complete the assembly of projection optical system C2,first lens barrel 201 and third lens barrel 203 are first fitted on theframe shown in FIG. 10. At this point, it may be difficult to make thepositional relationship of both lens barrels 201, 203 perfectly conformto the design data.

[0142] For deviations in the positional relationship between first lensbarrel 201 and third lens barrel 203, a deviation in height in thevertical Z direction, and a deviation in the interaxis distance in thehorizontal Y direction is considered. Among these, if there is adeviation in height in the vertical Z direction between first lensbarrel 201 and third lens barrel 203, the total axial length fromreticle R to the wafer W will deviate from the design data. In thiscase, the total length can be set in accordance with the design value byadjusting the height at which second lens barrel 202 is attached whenfitting second lens barrel 202 to auxiliary supports 208 a, 208 b.

[0143] If there is a deviation in the interaxis distance between firstlens barrel 201 and third lens barrel 203, it can be absorbed byadjusting in the horizontal Y direction the position at which secondlens barrel 202 is attached. Thus, by adjusting the position betweeneach barrel, projection optical system C2 can be assembled with ease inaccordance with the design data.

[0144] In apparatus 200 of FIG. 8, a plurality of optical membersarrayed along first optical axis Z1 are supported by one lens barrel201. Also, a plurality of optical members are arrayed along thirdoptical axis Z3 and are supported by one lens barrel 203. At least oneof first lens barrel 201 and third lens barrel 203 may have a splitconstruction, namely at least one of first lens barrel 201 and thirdlens barrel 203 may comprise a plurality of lens barrels.

[0145] As discussed above, the third mode for carrying out the presentinvention can provide a catadioptric optical system that does not invitedeterioration of the image and for which the assembly adjustment iseasy.

[0146] The following explains the fourth mode for carrying out thepresent invention, using FIGS. 12a, 12 b to FIGS. 14a, 14 b. The fourthmode for carrying out the present invention relates to a supportstructure 300 of a catadioptric-type projection optical system used in aprojection exposure apparatus. Furthermore, since the projection opticalsystem used in the projection exposure apparatus according to the fourthmode for carrying out the present invention is catadioptric opticalsystem C2 described in Table 3 and Table 4, mentioned above, theexplanation thereof is hereby omitted.

[0147]FIG. 12a is an XY plan view of support structure 300 that supportssystem C2, and FIG. 12b is a longitudinal cross-sectional view (YZcross-sectional view) of the support structure.

[0148] Projection optical system C2 of the fourth mode for carrying outthe present invention shown in FIG. 12 has three optical axes Z1, Z2,Z3. First optical axis Z1 is folded to second optical axis Z2 by firstplane mirror M1, and second optical axis Z2 is folded back to thirdoptical axis Z3 by second plane mirror M2. In other words, first planemirror M1 is arranged so that it passes through the point ofintersection of first optical axis Z1 and second optical axis Z2, andsecond plane mirror M2 is arranged so that it passes through the pointof intersection of second optical axis Z2 and third optical axis Z3.

[0149] As shown in FIG. 12b, the optical members arranged on firstoptical axis Z1 are held by first barrel 301, and the optical membersarranged on third optical axis Z3 are held by third barrel 303. Inaddition, first plane mirror M1 and second plane mirror M2 are held by asecond barrel 302.

[0150] At the time of projection and exposure, the light that passesthrough first barrel 301 is relayed through second barrel 302, isconducted to third barrel 303 and reaches image plane IP. Second barrel302 extends an arm from the vicinity of its center, and is directlyaffixed to a frame 305 so that second optical axis Z2 is horizontal.

[0151] The following explains the assembly adjustment method of theprojection optical system according to the fourth mode for carrying outthe present invention.

[0152] First, since first to third barrels 301 to 303 are independentstructures, they can each be assembled independently. In other words,since first barrel 301 and third barrel 303 do not include a planemirror, and the lenses and concave reflecting mirror MC are merely linedup with respect to one of optical axes Z1, Z3, assembly can be performedwith the same technique as that of a conventional dioptric system. Onthe other hand, since second barrel 302 holds plane mirrors M1, M2, andthe number of parts to be held is small, assembly adjustment can beperformed by using, for example, a three-dimensional measuring machine.

[0153] Next, the three barrels 301 to 303 are connected. Incidentally,if adjustments between the barrels are performed, deviations from thedesign values may arise. This error is not produced by conventionaldioptric system lenses. This deviation between barrels can also beeliminated up to a certain amount by using various adjustment mechanismsof the type used in conventional dioptric systems. However, if thedeviation between barrels is, for example, on the order of a millimeter,the adjustment stroke in conventional adjustment methods becomesinadequate, or the amount of residual high-order aberrationunfortunately increases even if within the adjustment stroke. Therefore,the design performance can no longer be realized. Consequently, it isnecessary to perform adjustments between barrels in advance up to themillimeter order. The following describes this procedure.

[0154] First, first barrel 301 and third barrel 303 are assembled intoframe 305. At this time, first barrel 301 and third barrel 303 areassembled so that they are as mutually parallel as possible. If opticalaxes Z1, Z3 are perpendicular to the holding surface of frame 305, it ispreferable since subsequent adjustment becomes easier.

[0155] As can be seen from the design data, positional relationships inthe predetermined design values exist between first barrel 301 and thirdbarrel 303, and it is necessary that these be satisfied on the micronorder. However, it is extremely difficult to install an object of largesize and heavy weight, like first and third barrels 301, 303, on amicron order from the outset. In addition, the inclination of first andthird barrels 301, 303 must also be on the order of a few seconds withrespect to one another, and this too is difficult to realize with justthe initial placement.

[0156] Accordingly, first barrel 301 or third barrel 303 may be providedwith a movement and inclination adjustment mechanism. Even in this case,it is quite difficult to adjust on the order of microns large and heavyobjects like first and third barrels 301, 303 with them mounted on frame305 as is. Consequently, a realistic procedure is one wherein firstbarrel 301 or third barrel 303 is first removed from frame 305, frame305 and the like are adjusted, and then first barrel 301 or third barrel303 is reattached. Consequently, first and third barrels 301, 303, asshown in FIG. 12b, are made removable in the working example by usingkinematic joint 306. It is therefore possible to remove first barrel 301or third barrel 303, adjust the thickness of the flange position, andthen reattach the barrel.

[0157] However, in the present working example, if first and thirdbarrels 301, 303 are inclined and adjusted on the order of a fewmicrons, then a deviation from the design value of the spacing betweenfirst and third barrels 301, 303, or a deviation from the design valueof the height in the upward or downward direction can be adjusted bymoving second barrel 302, if within the adjustment range of secondbarrel 302. In other words, a deviation in the spacing between first andthird barrels 301, 303 and a deviation in height can be adjusted to anoptical path length position equivalent to the design value by movingsecond barrel 302 vertically or horizontally.

[0158] As described above, if the optical members immediately afterreticle R or immediately before wafer W are not included, and secondbarrel 302 having one or more folding members is provided with anadjustment mechanism, then an adjustment mechanism in the other barrels301, 303 may become unnecessary. Accordingly, in the present mode forcarrying out the present invention, adjustment is performed using onlythe adjustment mechanism of second barrel 302.

[0159] Next, second barrel 302 is also installed on frame 305 at apredetermined position. However, as mentioned above, the deviation inspacing and the deviation in height of first and third barrels 301, 303are premeasured, and the amounts of those deviations are added as anoffset to the design value of second barrel 302. Even if the above valueis known, second barrel 302 is also quite large, and it is difficult toinstall with an accuracy on the order of microns and seconds from theideal position on the first installation. Consequently, the positionsbetween first to third barrels 301 to 303 are measured and, to correctthese, second barrel 302 is provided with a translation and inclinationmechanism.

[0160] In other words, as shown in the longitudinal cross-sectional view(YZ cross-sectional view) of second barrel 302 and frame 305 in FIG.13a, second barrel 302 is installed on frame 305 via washers 307 andballs 308. Washers 307 function as an adjustment mechanism, and balls308 function as a removal mechanism. In this case as well, it isdifficult to make an adjustment on the order of microns with secondbarrel 302 mounted as is on frame 305, as was shown with first and thirdbarrels 301, 303. Consequently, a practical procedure is one whereinsecond barrel 302 is first removed, washers 307 are adjusted, and secondbarrel 302 is reattached. Thus, it is effective to attach a removalmechanism to second barrel 302. In addition, second barrel 302 is thelightest barrel among the three barrels 301, 302, 303 shown in FIG. 12b.Consequently, its removal and adjustment is the easiest. Thus,adjustment is easiest if an adjustment means is provided for adjustingthe inclination and translation of the lightest barrel.

[0161] Next, optical adjustment is performed. This is carried out byperforming a fine adjustment of the lens spacings, and by inclining(tilting) or moving (shifting) in a direction perpendicular to theoptical axis one or a plurality of lenses. In this connection, the caseof a catadioptric system is disclosed in, for example, U.S. Pat. No.5,638,223. When performing optical adjustment of a catadioptric system,as disclosed in this reference, a mechanism is preferred that opticallyadjusts only the required optical element unit without affecting otheroptical element units as much as possible.

[0162] In accordance with this requirement in the present example, theoptical elements of first barrel 301 are further distributed and housedin a plurality of lens barrel units 311 to 314. Further, the opticalelements of third barrel 303 are distributed and housed in a pluralityof lens barrel units 331 to 333, as shown in FIG. 12b. furthermore, eachof lens barrel units 311 to 314, 331 to 333 house one or more opticalelement. These lens barrel units are provided with a mechanism thatmoves or inclines the lens barrel unit along the optical axis or in adirection orthogonal to the optical axis by making adjustments betweenthe lens barrel units.

[0163] The following describes the optical adjustment procedure for thiscase. First, the amount of aberration of the lens is measured by a printtest and the like. Based thereon, the amount of movement or inclinationof the lens barrel unit is indicated. Based on that, lens barrel units311 to 314, 331 to 333 of first and third barrels 301, 303 are moved.However, as can be seen from FIG. 12b, it is nearly impossible to movelens barrel units 311 to 314, 331 to 333 of first and third barrels 301,303 without removing second barrel 302. Accordingly, since second barrel302 is removable, as previously explained, second barrel 302 is removedand lens barrel units 311 to 314, 331 to 333 in first and third barrels301, 303 are moved in accordance with the indicated value. In this case,if first and third barrels 301, 303 are removable, first and thirdbarrels 301, 303 may be removed and adjusted on a separate adjustmentbench. An aspect of this is shown in FIG. 13b for the case of thirdbarrel 303.

[0164]FIG. 13b is a longitudinal cross-sectional view (YZcross-sectional view) of third barrel 303. In FIG. 13b, third barrel 303is further internally divided into three lens barrel units 331 to 333that include optical elements. In FIG. 13b, uppermost part and lowermostpart lens barrel units 331, 333 are affixed, and middle lens barrel unit332 is moved in the optical axis direction by replacing washers 307, andis also moved in the direction orthogonal to the optical axis. Aftercompleting the adjustment, first and third barrels 301, 303 areassembled and, lastly, second barrel 302 is returned to its originalposition.

[0165] By repeating the above optical adjustment one or more times, thelens performance approaches the design value.

[0166] Nevertheless, even if the above adjustment procedure is repeated,if second barrel 302 or the adjustment indication of first and thirdbarrels 301, 303 is reproduced, microscopic errors with respect to theindicated value inevitably arise. When adjusting aberrations due tothese errors, it is inevitable with just the above adjustment procedurethat second barrel 302 and first and third barrels 301, 303 must beremovable, which is extremely laborious. Consequently, it is preferablethat this portion of the final aberration adjustment be able to beperformed without removing the barrels. Furthermore, even after a lensis completed, for example, aberrations of the lens changemicroscopically due to mounting on the stage, movement when used as aproduct, and changes in the installation environment and the like. It isnecessary to perform this portion of the aberration adjustmentexternally without removing any barrels.

[0167] Consequently, the present working example enables the adjustmentof the five Seidel aberrations by changing at least five optical pathlengths, as disclosed in Japanese Patent Application Kokai No. Hei10-54932. Furthermore, decentered aberrations are made adjustable byproviding a function that inclines at least five sets of lens elementsor lens assemblies LA1 to LA5, without externally affecting otheroptical members. A technique to tilt a lens element or lens group isdisclosed in Japanese Patent Application Kokai No. Hei 10-133105. Inthis technique, a lens element near the reticle is tilted. However,although this mechanism is effective for a case like correctingdistortion due to decentering, it is inadequate for correcting coma dueto decentering. Moreover, the technique in Japanese Patent ApplicationKokai No. Hei 10-133105 is for a dioptric system, which is substantiallydifferent from the case wherein a catadioptric system lens is used, asin the present invention.

[0168] Lens assemblies LA1-LA5 are preferable in that making the lenselements or lens assemblies coincide is efficient for changing theoptical path length. The five lens elements or lens assemblies mentionedherein correspond to the five types of third order decenteredaberrations as described in the reference by Yoshiya MATSUI, entitled “AStudy of Third Order Aberrations in Optical Systems Wherein DecenteringExists,” 1990, Japan Optomechatronics Society, p. 5. Namely, these fiveaberrations include two types of decentered distortion, decenteredastigmatism, inclination of the image plane, and decentered coma. Byusing this optical path changing mechanism and decentered adjustmentmechanism, performance the same as the design value can ultimately berealized. These five sets of lens elements or lens assemblies LA1 to LA5are shown in FIG. 12b. In this manner, the mechanism that tilts the lenselements or lens assemblies is extremely effective, particularly in acatadioptric system.

[0169] This adjustment mechanism is shown in FIGS. 14a and 14 b. Avariety of mechanical mechanisms can be considered with regard to thisadjustment mechanism. FIG. 14a shows a mechanism that translates andtilts the lens elements and lens assemblies. Three adjustment rods 341protrude in the direction of 0°, 120°, and 240° from lens holder 340,and a vertical drive mechanism 343 is attached to each of the threeadjustment rods 341, which pass through the side wall of lens barrelunit 342. A piezoelectric device or ultrasonic motor can be used asvertical drive mechanism 343.

[0170] In addition, FIG. 14b shows a mechanism that tilts the lenselements or lens groups. Lens holder 340 is provided with X shafts 345that extend in the +X direction and −X direction. X shafts 345 arepivoted by intermediate barrel 346, provided with Y shafts 347 thatextend in the +Y direction and −Y direction. Y shafts 347 are pivoted bylens barrel unit 342, and rotational drive mechanisms 348 are attachedto X shafts 345 and Y shafts 347.

[0171] In this manner, it is essential that the catadioptric exposureapparatus having a plurality of optical axes have, as described above, aprocess that adjusts by an adjustment apparatus the mutual relationshipbetween optical axes Z1, Z2, Z3 for each of the barrels 301-303, aprocess that positions each of the lens barrel units 311 to 314, 331 to333, and a process that positions the simple lenses or lens assembliesLA1 to LA5. Having the above adjustment processes is essential so thatperformance in accordance with the design values can ultimately beachieved.

[0172] By the adjustment mechanism and adjustment process according tothe fourth mode for carrying out the present invention as explainedabove, a catadioptric projection exposure apparatus can be providedultimately having optical performance substantially equal to the designvalue.

[0173] Next, the fifth mode for carrying out the present invention willbe explained, referencing FIGS. I5 a and 15 b. The fifth mode forcarrying out the present invention relates to a support method suitablefor, for example, supporting second lens barrel 302 in the third modefor carrying out the present invention.

[0174]FIG. 15a is an optical path diagram of a fifth embodiment of aprojection optical system C3 for carrying out the present invention.Projection optical system C3 forms an intermediate image S of thepattern on reticle R located in object plane OP by first imaging opticalsystem A. Intermediate image S is then imaged onto the photosensitivesurface located in image plane IP of wafer W by second imaging opticalsystem B. Furthermore, first imaging optical system A comprises a frontgroup Al, and a rear group A2 that constitutes a round-trip opticalsystem. The optical specifications for the projection optical systemshown in FIG. 15a are those of system C2 and are listed in Table 3 andTable 4 above. Furthermore, exposure region EA on wafer W is an oblongregion (slit-shaped region) measuring 25 mm in the X direction and 6 mmin the Y direction, as shown in FIG. 15b. FIG. 15b is an enlarged viewtaken in the direction of the arrows along the line 15 b-15 b in FIG.15a.

[0175] Plane mirrors M1, M2 in the present working example are held bysecond lens barrel 302 as a single holding member. In other words, planemirrors M1, M2 are held as a single body. Second lens barrel 302 issupported from the front (+X direction) and from the rear (−X direction)by support members 308 a, 308 b that are provided in a standingcondition on frame 305, the same as in the third mode for carrying outthe present invention discussed earlier.

[0176] In FIG. 15a, if the point of intersection of first optical axisZ1 and second optical axis Z2 is assigned point P, then point P lies ina plane that includes the reflecting surface of first plane mirror M1.If the point of intersection of second optical axis Z2 and third opticalaxis Z3 is assigned point Q, then point Q lies in a plane that includesthe reflecting surface of second plane mirror M2. Line segment PQconstitutes second optical axis Z2.

[0177] The midpoint of the positions where support members 308 a, 308 b,shown in FIG. 10, support second lens barrel 302 is generally at apivotal point G located 30 mm directly below a midpoint K of secondoptical axis Z2 (namely, line segment PQ). Although support members 308a, 308 b provide support so that no motion whatsoever arises in secondlens barrel 302, in actuality, there is a possibility that rotationalmotion will arise in second lens barrel 302. This rotational motion isabout the X axis, Y axis and Z axis through which pivotal point Gpasses.

[0178] In this manner, plane mirrors M1, M2 are held as a single body,and the following describes the effectiveness of configuration whereinmidpoint K or that vicinity of second optical axis Z2 (line segment PQ)is set to pivotal point G. For comparative purposes, consider the casewherein plane mirrors M1, M2 are supported separately, and examine thedistortion of the image when first plane mirror M1 is rotated, and thedistortion in the image when second plane mirror M2 is rotated. Then,examine the distortion of the image when both plane mirrors M1, M2 arerotated as a single body, based on the construction of the presentworking example.

[0179] The amount of distortion of the image depends on how much centerposition IP1 of exposure region EA and positions IP2 to IP5 at the fourcorners, as shown in FIG. 15b, are moved before and after rotation ofplane mirror M1. Accordingly, exposure region EA is an oblong shapemeasuring 25 mm×6 mm, as mentioned earlier, and center position IP1 ofexposure region EA in the image plane is at a position deviated fromthird optical axis Z3 by 5+3=8 mm in the Y direction.

[0180] First, the results of the distortion of the image when firstplane mirror M1 is rotated independently will be explained. Let thehypothetical rotational motion be about the X axis, Y axis and Z axisthrough which pivotal point P passes, with the point of intersection Pof first optical axis Z1 and second optical axis Z2 as the pivotalpoint. The direction of rotation and rotational angle is 3″ in thecounterclockwise direction viewed from the +X direction, 3″ in thecounterclockwise direction viewed from the +Y direction, and 3″ in theclockwise direction viewed from the +Z direction. Furthermore, pivotalpoint P is in the plane wherein the reflecting surface of first planemirror M1 extends. However, it is not the case that pivotal point P lieson the reflecting surface of first plane mirror M1 itself because firstimaging optical system A includes a round-trip optical system.

[0181] The image is deformed due to this rotational motion. Table 6shows the amount of displacement of center position IP1 of exposureregion EA and four corners IP2 to IP5 of exposure region EA.

[0182] Furthermore, if first plane mirror M1 is rotated, the position onthe wafer surface of third optical axis Z3 will also displaced. Thecontents of Table 6 show the remaining amount of displacement of pointsIP1 to IP5 when the post-displacement position of third optical axis Z3is drawn back so that it superposes the pre-displacement position ofthird optical axis Z3.

[0183] Likewise, Table 7 shows the distortion of the image when secondplane mirror M2 is rotated independently. The pivotal point is the pointof intersection Q of second optical axis Z2 and third optical axis Z3,and the other conditions are the same as described above.

[0184] Likewise, Table 8 shows the distortion of the image when bothplane mirrors M1, M2 are rotated as a single body. The pivotal point ispoint G, which lies 30 mm directly below midpoint K of second opticalaxis Z2 (line segment PQ), and the other conditions are the same asdescribed above. The unit of displacement amounts dX, dY shown in Table6 to Table 8 is nm. TABLE 6 COMPARATIVE EXAMPLE: ROTATION ONLY OF FIRSTPLANE MIRROR M1 Rotation Rotation Rotation About X Axis About Y AxisAbout Z Axis dX dY dX dY dX dY IP1 0 −14 −106.7 0 106.7 0 IP2 73.2 19.2−159.7 −145.3 159.7 145.2 IP3 32.9 41.5 −86.5 −165.4 86.5 165.3 IP4−73.1 19.2 −159.8 145.2 159.7 −145.3 IP5 −32.9 41.5 −86.5 165.3 86.5−165.4

[0185] TABLE 7 COMPARATIVE EXAMPLE: ROTATION ONLY OF SECOND PLANE MIRRORM1 Rotation Rotation Rotation About X Axis About Y Axis About Z Axis dXdY dX dY dX dY IP1 0 −7.7 124.8 0 −124.8 0 IP2 −19.9 −56.1 185.5 191.7−185.5 −191.7 IP3 −9.1 −44.3 85.5 186.3 −85.4 −186.3 IP4 19.9 −56.1185.5 −191.7 −185.5 191.7 IP5 9.1 −44.3 85.4 −186.3 −85.5 186.3

[0186] TABLE 8 PRESENT WORKING EXAMPLE: FIRST AND SECOND PLANE MIRRORSM1, M2 ROTATED AS A SINGLE BODY Rotation Rotation Rotation About X AxisAbout Y Axis About Z Axis dX dY dX dY dX dY IP1 0 −10.9 18.1 0 231.5−0.1 IP2 26.7 −18.4 25.7 46.5 345.3 336.9 IP3 12 −1.4 −1.1 21 172.1351.6 IP4 −26.7 −18.4 25.8 −46.4 345.1 −337 IP5 −12 −1.4 −1 −20.9 171.9−351.7

[0187] As shown in Table 6 to Table 8 above, distortion of the imagearises when the target member is rotated about the X axis. In addition,rotation of the image arises if the target member is rotated about the Yaxis or if rotated about the Z axis. Among these, consider firstrotation about the X axis. It can be seen that distortion of the imagein the present working example (example of Table 8, Rotation About XAxis) is smaller than independent rotation of first plane mirror M1(example of Table 6, Rotation About X Axis) and independent rotation ofsecond plane mirror M2 (example of Table 7, Rotation About X Axis). Inother words, since image distortion when first plane mirror M1 isindependently rotated and image distortion when second plane mirror M2is independently rotated tend to be in substantially the reversedirections, they are both canceled. Image distortion is thereby reducedin the present working example. This is because nearly no deviationoccurs in the ray with respect to the ideal position and the amount ofaberration generated is small, since the two optical axes Z1, Z3 do notmutually deviate even if plane mirrors M1, M2 deviate at the same angle.

[0188] For the case where plane mirrors M1, M2 are held as a singlebody, it is preferable to make the pivotal point midpoint K of secondoptical axis Z2 (line segment PQ). This is because, if the pivotal pointis at midpoint K of second optical axis Z2 (line segment PQ), the axialdistance from reticle R to wafer W does not change even if the holdingmember through which the pivotal point passes is rotated about the Xaxis. Therefore, almost no rotationally symmetric aberrations ormagnification deviation occurs.

[0189] On that basis, it is preferable that distance KG between midpointK of second optical axis Z2 (line segment PQ) and pivotal point G besmall and, generally, it is preferable that it be within 0.2 timeslength PQ of second optical axis Z2, or:

KG≦0.2×PQ  (5)

[0190] Condition (5) is satisfied in the present working example, sinceKG=30 mm and PQ=530 mm.

[0191] With continuing reference to FIG. 15a, pivotal point G is insidea holding member (e.g., barrel 302). The holding member can only providesupport at an external surface thereof. Accordingly, a realistic supportposition for the holding member is in the vicinity of the plane thatpasses through midpoint K of second optical axis Z2 and is orthogonal tosecond optical axis Z2.

[0192] Now considered is rotation about the Y axis. It can be seen thatrotation of the image in the present working example (example of Table8, Rotation About Y Axis) is smaller than independent rotation of firstplane mirror M1 (example of Table 6, Rotation About Y Axis) andindependent rotation of second plane mirror M2 (example of Table 7,Rotation About Y Axis). In other words, since rotation of the image whenfirst plane mirror M1 is independently rotated and rotation of the imagewhen second plane mirror M2 is independently rotated tend to be insubstantially the reverse directions, both are canceled and rotation ofthe image is reduced in the present working example.

[0193] Now considered is rotation about the Z axis. Rotation of theimage is unfortunately generated to a great extent in the presentworking example (example of Table 8, Rotation About Z Axis) comparedwith independent rotation of first plane mirror M1 (example of Table 6,Rotation About Z Axis) and independent rotation of second plane mirrorM2 (example of Table 7, Rotation About Z Axis).

[0194] However, since lens barrel 302 that holds plane mirrors M1, M2 asa single body has its direction of length in the Y direction, the amountof rotation about the Z axis (and amount of rotation about the X axis)can be easily controlled by strengthening support member 300 at the edgeof the length direction of holding member H, and the like. Furthermore,since the direction of gravity is in the direction of the Z axis, thegravity balance of holding member H is not disturbed even if rotationabout the Z axis occurs. Accordingly, based also on this point, theamount of rotation about the Z axis can be easily controlled.

[0195] As can be seen from the present working example, if the foldingmember is a surface reflecting mirror, holding is comparatively easy. Incontrast, if an element like a beam splitter is included, it isunpreferable since the weight of the holding member increases andsupport of the holding member becomes comparatively difficult.

[0196] Furthermore, although second lens barrel 302 as a holding membersupports only folding members M1, M2 in the fifth mode for carrying outthe present invention, a lens (not shown in FIG. 15a) as a dioptricoptical member may also be interposed between folding members M1, M2held by second lens barrel 302. An example of such a case will beexplained, referencing FIG. 16.

[0197] With reference now to FIG. 16a, which is an optical path diagramof the projection optical system C4 according to the sixth mode forcarrying out the present invention, the principal points of differencefrom the projection optical system C3 of FIG. 15 mentioned earlier arethat a lens L is arranged between plane mirrors M1, M2, and that theglass material of all lenses is quartz glass.

[0198] The following lists the principal specifications of projectionoptical system C4 according to the sixth mode for carrying out thepresent invention.

[0199] N.A. on wafer side: 0.65

[0200] Magnification: 0.25×

[0201] Working wavelength: 193.3 nm (ArF excimer laser)

[0202] Exposure region EA is an oblong region measuring 25 mm in thelongitudinal X direction and 8 mm in the horizontal Y direction, asshown in FIG. 16b.

[0203] Table 9 and Table 10 below list the specifications of the opticalmembers projection optical system C4 according to the sixth mode forcarrying out the present invention. Since the glass material of alllenses is quartz, such is omitted from Table 9. In addition, an opticalsurface to which an asterisk (*) is appended to the surface number inTable 9 indicates an aspherical surface, and the radius of curvature foraspherical surfaces in Table 9 indicates the vertex radius of curvature.The aspherical surface shape is represented by condition (a), above. Foreach aspherical surface, the conical coefficient κ is 0, and E and Famong the aspherical coefficients are 0. Consequently, the asphericalsurface data for Table 10 is not listed. TABLE 9 SIXTH MODE FOR CARRYINGOUT THE PRESENT INVENTION S R d Re Material 0 ∞ 52.5105 R 1 567.143040.1245 84.49 A1 2 3470.8704 2.2743 86.20 3 12580.6849 29.5354 86.34 A14 919.5973 2.0000 88.19 5 355.8404 35.8420 89.51 A1 6 645.8193 78.213389.37 7 523.4723 23.5558 95.17 A2 8 −1724.9806 14.1444 94.91 9 −544.715222.0000 94.37 A2 10 −996.4488 0.5000 94.96 11 222.1244 22.0000 94.48 A212 285.0673 270.9667 91.66 13 −448.3590 20.0001 69.82 A2 14 483.24377.1773 69.86 15 450.0000 27.4588 73.46 A2 16 −581.8071 98.1108 77.12 17−164.5653 25.0000 97.01 A2 18 −686.3758 18.1361 116.87 19 −274.4169−18.1361 117.82 A2 MC 20 −686.3758 −25.0000 117.22 A2 21 −164.5653−98.1108 102.36 22 −581.8071 −27.4588 99.27 A2 23 450.0000 −7.1773 98.5524 483.2437 −20.0001 96.16 A2 25 −448.3590 −270.9667 92.30 26 285.0673−22.0000 83.28 A2 27 222.1244 −0.5000 84.79 28 −996.4488 −22.0000 82.76A2 29 −544.7152 −14.1444 80.48 30 −1724.9806 −23.5558 79.87 A2 31523.4723 −0.5000 78.99 32 ∞ 255.9374 M1 33 604.6543 31.2039 116.51 B L34 −787.6549 200.0000 116.86 35 ∞ −152.7463 M2 36 −445.7714 −30.0000103.97 B 37 −10477.3479 −0.5000 102.01 38* −704.6939 −24.4152 101.24 B39 −217.6002 −46.6658 96.30 40 −262.5805 −32.4068 100.37 B 41 −1345.5908−82.6445 98.92 42 — −47.7302 91.14 AS 43 −313.2008 −39.4658 97.58 B 44584.6659 −0.8283 97.17 45 −473.1823 −27.4850 94.61 B 46 487.4609 −8.093293.17 47 304.5680 −25.0000 92.05 B 48* 1295.3943 −0.6535 87.95 49−210.3586 −42.6899 84.21 B 50 −716.6193 −4.1246 76.28 51 −240.1793−60.0000 72.13 B 52 1038.2875 −1.1901 55.47 53 −280.1800 −40.0000 50.65B 54 −2803.1853 −18.2145 34.10 55 ∞ W

[0204] TABLE 10 ASPHERICAL DATA OF THE SIXTH MODE FOR CARRYING OUT THEPRESENT INVENTION 38^(th) Surface A =   2.1892 × 10⁻⁸ B =   2.7825 ×10⁻¹³ C =   1.4089 × 10⁻¹⁸ D = −6.4967 × 10⁻²³ 48^(th) Surface A =−1.3381 × 10⁻⁸ B = −4.2757 × 10⁻¹³ C =   4.5484 × 10⁻¹⁸ D = −2.4978 ×10⁻²²

[0205] For comparative purposes, as in system C3 of FIGS. 15a and 15 b,consider the case wherein plane mirrors M1, M2 are separately supported,and examine the distortion of the image when first plane mirror M1 isrotated and the distortion of the image when second plane mirror M2 isrotated. Subsequently, next examined is the distortion of the image whenplane mirrors M1, M2 are rotated as a single body, based on theconfiguration of the present working example.

[0206] Table 11 shows the distortion of the image when first planemirror M1 is independently rotated. The pivotal point is the point ofintersection P of first optical axis Z1 and second optical axis Z2, andother conditions are the same as those in the fifth mode for carryingout the present invention.

[0207] Table 12 shows the distortion of the image when second planemirror M2 is independently rotated. The pivotal point is the point ofintersection (2 of second optical axis Z2 and third optical axis Z3, andother conditions are the same as those above.

[0208] Table 13 shows the distortion of the image when plane mirrors M1,M2 are rotated as a single body. The pivotal point is point G located+50 mm in the Z direction and −10 mm in the Y direction from midpoint Kof second optical axis Z2 (line segment PQ), and other conditions arethe same as those above. Furthermore,

KG=[50²+(−10)²]^(½)=51

[0209] and since PQ is 487 mm, condition (5) is satisfied. TABLE 11COMPARATIVE EXAMPLE: ROTATION ONLY OF FIRST PLANE MIRROR M1 RotationRotation Rotation About X Axis About Y Axis About Z Axis dX dY dX dY dXdY IP1 0 −9.8 −120.1 0 120.1 0 IP2 63.4 20.4 −176.2 −150.2 176.3 150.1IP3 24.3 38.4 −78.8 −169.7 78.9 169.7 IP4 −63.4 20.4 −176.3 150.1 176.2−150.2 IP5 −24.3 38.4 −78.9 169.7 78.8 −169.7

[0210] TABLE 12 COMPARATIVE EXAMPLE: ROTATION ONLY OF SECOND PLANEMIRROR M2 Rotation Rotation Rotation About X Axis About Y Axis About ZAxis dX dY dX dY dX dY IP1 0 0.9 139.8 0 −139.8 0 IP2 −38.4 −32.3 206.8201 −206.7 −210 IP3 −14.7 −34.3 74.5 189.1 −74.5 −189.1 IP4 38.4 −32.3206.7 −201 −206.8 201 IP5 14.7 −34.3 74.5 −189.1 −74.5 189.1

[0211] TABLE 13 PRESENT WORKING EXAMPLE: FIRST AND SECOND PLANE MIRRORSM1, M2 ROTATED AS A SINGLE BODY Rotation Rotation Rotation About X AxisAbout Y Axis About Z Axis dX dY dX dY dX dY IP1 0 −31 19.7 0 259.9 −0.1IP2 49.4 −44.1 30.6 50.8 390.6 343.2 IP3 41.8 −12.6 −4.2 19.4 160.9355.8 IP4 −49.4 −44.1 30.3 −50.8 390.4 −343.4 IP5 −41.8 −12.6 −4.5 −19.4160.7 −355.9

[0212] As shown in Table 11 to Table 13 above, distortion of the imagearises when the target member is rotated about the X axis. Rotation ofthe image arises if the target member is rotated about the Y axis or ifrotated about the Z axis. Among these, first considered is rotationabout the X axis. Substantially the same amount of image distortion isgenerated in the present working example (example of Table 13, RotationAbout X Axis) as with independent rotation of first plane mirror M1(example of Table 11, Rotation About X Axis) and with independentrotation of second plane mirror M2 (example of Table 12, Rotation AboutX Axis). This is because, since lens L is interposed between planemirrors M1, M2, rays reflected by first plane mirror M1 are deviated bypassing through lens L and subsequently impinge on second plane mirrorM2. Consequently, aberrations are generated since the effect wherein theoptical axis is undeviated is unfortunately lost.

[0213] The length direction of second lens barrel 302 is the Ydirection, as mentioned previously. Hence, the amount of rotation aboutthe X axis can be easily controlled by reinforcing the support member atthe edge of the length direction of second lens barrel 302, and thelike. Nevertheless, if holding plane mirrors M1, M2, which form a rightangle as a single body, it is preferable that lens L not be providedtherebetween. Even in the case where lens L is arranged, it ispreferable to limit such to two members.

[0214] Next, consider rotation about the Y axis. It can be seen thatrotation of the image in the present working example (example of Table13, Rotation About Y Axis) is smaller than independent rotation of firstplane mirror M1 (example of Table 11, Rotation About Y Axis) andindependent rotation of second plane mirror M2 (example of Table 12,Rotation About Y Axis). In other words, since rotation of the image whenfirst plane mirror M1 is independently rotated and rotation of the imagewhen second plane mirror M2 is independently rotated tend to be insubstantially the reverse directions, they are both canceled, androtation of the image is thereby reduced in the present working example.

[0215] Next, consider rotation about the Z axis. A large rotation ofimage is generated in the present working example (example of Table 13,Rotation About Z Axis) compared with independent rotation of first planemirror M1 (example of Table 11, Rotation About Z Axis) and independentrotation of second plane mirror M2 (example of Table 12, Rotation AboutZ Axis). However, as discussed above, the amount of rotation about the Zaxis can be controlled easily.

[0216] As explained above, the fifth and sixth modes for carrying outthe present invention reduce the amount of image distortion generated byrotation of the folding member and, accordingly, can obtain a stabilizedhigh resolution.

[0217] Next, the seventh mode for carrying out the present inventionwill be explained,.referencing FIG. 17 to FIG. 19a and 19 b.

[0218]FIG. 17 shows a schematic of the configuration of a projectionoptical system 400 for implementing the alignment method andmanufacturing method according to the seventh mode for carrying out thepresent invention. The seventh mode for carrying out the presentinvention is related to a relative alignment method between a pluralityof lens barrel axes and folding members in a catadioptric-typeprojection optical system having two folding members, and amanufacturing method for a projection optical system (optical systemhaving folding members) that uses this alignment method.

[0219] In FIG. 17, the Z axis is set parallel to optical axis Z1 offirst imaging optical system A, the Y axis is set parallel to the papersurface of FIG. 17 in a plane perpendicular to the Z axis, and the Xaxis is set perpendicular to the paper surface of FIG. 17 in a planeperpendicular to the Z axis. Furthermore, the YZ plane, which is thepaper surface of FIG. 17, is a plane that includes optical axis Z1 offirst imaging optical system A and optical axis Z3 of second imagingoptical system B.

[0220] Projection optical system 400 in FIG. 17 is provided with firstimaging optical system A to form the intermediate image of the patternbased on the light from mask R, whereon a fine circuit pattern, forexample, is formed. Second imaging optical system B to form a reducedimage of the pattern onto wafer W, which is a photosensitive substrate,based on the light from the intermediate image. First folding mirror M1arranged in the vicinity of the position where the intermediate image isformed, and to fold in the +Y direction the light that passes throughfirst imaging optical system A. Second folding mirror M2 is provided tofold the light from first folding mirror M1 in the +Z direction towardsecond imaging optical system B.

[0221] First imaging optical system A comprises, in order from reticleR, three lens components L1 to L3 and concave reflecting mirror MC,shown by solid lines in the drawing. Furthermore, each of lenscomponents L1 to L3 and concave reflecting mirror MC is arrayed insidecylindrical first lens barrel 401 along one optical axis Z1 parallel tothe Z axis. Namely, optical axis Z1 of first imaging optical system Aand the axis of first lens barrel 401 coincide.

[0222] On the other hand, second imaging optical system B comprises, inorder from reticle R (namely, the second folding mirror side), five lenscomponents L4 to L8, as shown by solid lines in the drawing.Furthermore, each of the lens components L4 to L8 is arrayed insidecylindrical second lens barrel 403 along one optical axis Z3 parallel tothe Z axis, In other words, optical axis Z3 of second imaging opticalsystem B and the axis of second lens barrel 403 coincide. In addition,optical axis Z3 of second imaging optical system B and optical axis Z1of first imaging optical system A are mutually parallel.

[0223] Furthermore, first folding mirror M1 and second folding mirror M2arranged in the optical path between first imaging optical system A andsecond imaging optical system B have reflecting surfaces inclined byjust 45° with respect to optical axis Z1 and optical axis Z3 so thatthey are mutually opposing and so that they are orthogonal to the YZplane (paper surface of FIG. 17) that includes optical axis Z1 of firstimaging optical system A and optical axis Z3 of second imaging opticalsystem B. In other words, the reflecting surface of first folding mirrorM1 and the reflecting surface of second folding mirror M2 are mutuallyorthogonal, and the line of intersection formed extending along the tworeflecting surfaces is parallel to the X axis. First folding mirror M1and second folding mirror M2 are attached to a support body 402.

[0224] Thus, projection optical system 400 is a catadioptric-typeoptical system having two folding mirrors M1, M2, and has two lensbarrels 401, 403 having different axes. According to another viewpoint,projection optical system 400 has three different optical axes, namelyoptical axis Z1 of first imaging optical system A, optical axis Z3 ofsecond imaging optical system B, and third optical axis Z2 parallel tothe Y axis. In the present mode for carrying out the present invention,optical axis Z2 is defined as the tracing of a ray entering alongoptical axis Z1 to the reflecting surface of first folding mirror M1(strictly speaking, the extended surface of the effective reflectingregion) aligned at a predetermined position. In addition, optical axisZ2 is likewise defined as the tracing of a ray entering along opticalaxis Z3 to the reflecting surface of second folding mirror M2 aligned ata predetermined position.

[0225] In projection optical system 400, the light from the patternregion decentered from optical axis Z1 in the −Y direction on reticle Rpositioned parallel to the XY plane is reflected by concave reflectingmirror MC via each of the lens components L1 to L3 that constitute firstimaging optical system A. The latter then forms an intermediate imagevia each of the lens components L3 to L1. The light from theintermediate image is reflected in the +Y direction by the reflectingsurface of first folding mirror M1, is then reflected in the +Zdirection by the reflecting surface of second folding mirror M2 and isthen guided to second imaging optical system B. The light guided tosecond imaging optical system B passes through each of the lenscomponents L4 to L8, and then forms a reduced image of the mask patternin the exposure region, decentered from optical axis Z3 in the +Ydirection, on wafer W positioned parallel to the XY plane.

[0226] In projection optical system 400, as well as in the above modefor carrying out the present invention, first lens barrel 401 and secondlens barrel 403 can be positioned with high precision so that the axisof first lens barrel 401 and the axis of second lens barrel 403 aremutually parallel and spaced apart by a predetermined spacing. Inaddition, first and second folding mirrors M1, M2 can be positioned withhigh precision with respect to support member 402 so that theirreflecting surfaces are mutually orthogonal. Furthermore, thepositioning of first and second folding mirrors M1, M2 is discussedlater.

[0227] As discussed earlier, when positioning each of the opticalmembers L1 to L3, MC with respect to first lens barrel 401, the axis offirst lens barrel 401 and the optical axes of each of the opticalmembers L1 to L3, MC of first imaging optical system A can be made tocoincide with an accuracy in units of microns. Likewise, whenpositioning each of the optical members L4 to L8 with respect to secondlens barrel 403, the axis of second lens barrel 403 and the optical axesof each of the optical members L4 to L8 of second imaging optical systemB can be made to coincide with an accuracy in units of microns.

[0228] Accordingly, to position each of the optical members L1 to L8,MC, M1, M2 with high precision when manufacturing projection opticalsystem 400, it is necessary to align the relative positions of foldingmirrors M1, M2 and the two optical axes Z1, Z3 with high precision. Inother words, the relative positions of first lens barrel 401 having anaxis coincident with optical axis Z1, second lens barrel 403 having anaxis coincident with optical axis Z3, and folding mirrors M1, M2 must bealigned with high precision. Specifically, folding mirrors M1, M2 mustbe aligned with high precision with respect to the two lens barrels 401,403 so that, for example, the distance along optical axes Z1, Z2, Z3from reference point RA, which is the center of first lens barrel 401,to reference point RB, which is the center of second lens barrel 403, isa predetermined length.

[0229]FIG. 18a is a view that corresponds to FIG. 17, and is a drawingfor explaining the alignment method of the seventh mode for carrying outthe present invention.

[0230]FIG. 18a shows first lens barrel 401 and second lens barrel 403already positioned with high precision. In the present mode for carryingout the present invention, folding mirrors M1, M2 are aligned with highprecision with respect to first lens barrel 401 and second lens barrel403 when manufacturing the projection optical system. Subsequently, theother optical members are positioned with respect to first lens barrel401 and second lens barrel 403. Furthermore, the X axis, Y axis and Zaxis in FIG. 18a are set in the same manner as in FIG. 17.

[0231] In the alignment method of the present working example, a concavereflecting mirror MO having a reflecting surface MS1 is attached at apredetermined position inside first lens barrel 401 so that the opticalaxis thereof coincides with the axis of first lens barrel 401 (and inturn, optical axis Z1), as shown in FIG. 18a. Accordingly, reflectingsurface MS1 is formed as an aspherical surface and, in a state whereinconcave reflecting mirror MO is attached to first lens barrel 401, facesthe first folding mirror side.

[0232] As shown in FIG. 18a, a lens group FL as the optical element foradjustment is attached at a predetermined position inside second lensbarrel 403 so that the optical axis thereof coincides with the axis ofsecond lens barrel 403 (and in turn, optical axis Z3). The lens surfacemost on the second folding mirror side of lens group FL in a statewherein it is attached to second lens barrel 403 constitutes a referencesurface BS1 as the Fizeau reference surface.

[0233] Techniques to make the optical axis of concave reflecting mirrorMO and the axis of first lens barrel 401, as well as the optical axis oflens group FL and the axis of second lens barrel 403 coincide with anaccuracy in units of microns, are widely known. In addition, radius ofcurvature R of reflecting surface MS1, and distance F along the opticalaxis from the focal point on the reference surface BS1 side of lensgroup FL to reference surface BS1 can be accurately premeasured inaccordance with the prior art. Furthermore, distance 430 a along theoptical axis from reference point RA to reflecting surface MS1, anddistance 430 b along the optical axis from reference point RB toreference surface BS1 can also be accurately measured based on prior artusing, for example, a digital micrometer and the like.

[0234] In the present working example, concave reflecting mirror MO andlens group FL are respectively positioned with respect to first lensbarrel 401 and second lens barrel 403 so that the relationship shown incondition (h) below holds.

LD=430a+430b+R+F.  (h)

[0235] Therein, LD is the design distance (distance specified based onthe design) along the optical axis from reference point RA to referencepoint RB.

[0236] Accordingly, in the state wherein folding mirrors M1, M2 areaccurately aligned with respect to first lens barrel 401 and second lensbarrel 403, the focal point of concave reflecting mirror MO (namely, thepoint removed by just radius of curvature R along the optical axis fromreflecting surface MS1) and the focal point of lens group FL (namely,the point removed by just distance F along the optical axis fromreference surface BS1) coincide. In other words, if a parallel lightbeam parallel to optical axis Z3 on the wafer side of lens group FL isguided to lens group FL in this state, the light beam that passesthrough lens group FL and second folding mirror M2 converges at point424 on optical axis Z2 (namely, the focal point of lens group FL and thefocal point of concave reflecting mirror MO). The divergent light beamfrom convergent point 424 passes through first folding mirror M1 andperpendicularly impinges upon concave reflecting mirror MO. The lightbeam reflected by reflecting surface MS1 of concave reflecting mirror MOreconverges at point 424 via first folding mirror M1 along an opticalpath completely the same as the going path, and then changes to aparallel light beam parallel to optical axis Z3 via second foldingmirror M2 and lens group FL.

[0237] In other words, in the state wherein folding mirrors M1, M2 areaccurately aligned with respect to first lens barrel 401 and second lensbarrel 403, a predetermined interference fringe is obtained between thefirst light beam that returns after being reflected by reference surfaceBS1 without transmitting through reference surface BS1 of lens group FLand the second light beam that returns after transmitting throughreference surface BS1 of lens group FL and being reflected by concavereflecting mirror MO. Accordingly, in the present working example,folding mirrors M1, M2 are aligned with respect to first lens barrel 401and second lens barrel 403 based on the interference between the firstlight beam and the second light beam mentioned above. The followingexplains the detection of the interference between the first light beamand the second light beam, and the alignment of folding mirrors M1, M2.

[0238] First, the detection of the interference between the first lightbeam and the second light beam will be explained.

[0239] With continuing reference to FIG. 18a, parallel light, suppliedfrom interferometer 421 passes through opening 422 formed in second lensbarrel 403, and is guided to the inside of second lens barrel 403. Theparallel light beam guided to the inside of second lens barrel 403 isfolded in the −Z direction by reflecting mirror 423 attached to theinside of second lens barrel 403, and enters lens group FL unchanged asparallel light. To make the convergent point of the parallel light beamthat entered lens group FL coincident with the focal point of lens groupFL (point on optical axis Z2), the parallel light beam parallel tooptical axis Z3 must enter lens group FL. Accordingly, in addition toproviding interferometer 421 with a function to detect the interferencebetween the first light beam and the second light beam, it is providedwith an adjustment function that injects into lens group FL the parallellight beam parallel to optical axis Z3.

[0240]FIG. 18b shows the internal construction of interferometer 421shown in FIG. 18a. As shown in FIG. 18b, interferometer 421 is providedwith laser light source 431 that supplies coherent parallel light.First, when performing the incident adjustment of the parallel lightbeam, the light supplied from laser light source 431 is reflected in the−Z direction by beam splitter 432, and then impinges on adjustmentreflecting mirror 433 rotatable about two axes. The light reflected inthe −Y direction by adjustment reflecting mirror 433 enters lens groupFL (not shown in FIG. 18b) via opening 422 formed in second lens barrel403 and via reflecting mirror 423. The light reflected by referencesurface BS1 of lens group FL impinges on beam splitter 432 viareflecting mirror 423 and adjustment reflecting mirror 433. Thereflected light from reference surface BS1 that impinges on beamsplitter 432 is transmitted through beam splitter 432, and then impingeson detector 434. Furthermore, the light that transmitted throughreference surface BS1 of lens group FL is shaded by a shutter (notshown) installed in the optical path between, for example, lens group FLand second folding mirror M2.

[0241] Of the light supplied from laser light source 431, the lighttransmitted through beam splitter 432 passes through shutter 435 andthen perpendicularly impinges on reflecting mirror 136. The lightreflected by reflecting mirror 436 impinges on beam splitter 432 viashutter 435. The reflected light from reflecting mirror 436 thatimpinged on beam splitter 432 is reflected by beam splitter 432 and thenimpinges on detector 434. Thus, the interference fringe between thereflected light from reference surface BS1 and the reflected light fromreflecting mirror 436 that functions as a Twyman mirror is detected atdetector 434.

[0242] If the parallel light beam parallel to optical axis Z3 enterslens group FL, the parallel light beam perpendicularly impinges onreference surface BS1 of lens group FL. As a result, a predeterminedinterference fringe is detected in detector 434 between the reflectedlight from reference surface BS1 and the reflected light from reflectingmirror 436. By rotationally jogging adjustment reflecting mirror 433based on the interference fringe detected in detector 434, the parallellight beam parallel to optical axis Z3 can be injected into lens groupFL. In this manner, after performing the incident adjustment of theparallel light beam with respect to lens group FL, the interferencebetween the first light beam and the second light beam is detected in astate wherein shutter 435 is closed.

[0243] In other words, when detecting the interference between the firstlight beam and the second light beam, the light supplied from laserlight source 131 is reflected in the +Z direction by beam splitter 432and then enters lens group FL via adjustment reflecting mirror 433 andreflecting mirror 123. The first light beam reflected by referencesurface BS1 of lens group FL impinges on beam splitter 432 viareflecting mirror 123 and adjustment reflecting mirror 433. The firstlight beam, which is the reflected light from reference surface BS1 thatimpinged on beam splitter 432, is transmitted through beam splitter 432and then impinges on detector 434.

[0244] Referring once again to FIG. 18A, the second light beamtransmitted through reference surface BS1 of lens group FL is reflectedby second folding mirror M2, converges once and impinges on concavereflecting mirror MO via first folding mirror M1. The second light beamreflected by reflecting surface MS1 of concave reflecting mirror MOconverges once via first folding mirror M1, and then enters lens groupFL via second folding mirror M2. The second light beam that enters lensgroup FL impinges on beam splitter 432 via reflecting mirror 123 andadjustment reflecting mirror 433. The second light beam, which is thereflected light from reflecting surface MS1 of concave reflecting mirrorMO that impinged on beam splitter 432, is transmitted through beamsplitter 432, and then impinges on detector 434. Thus, the interferencefringe between the first light beam, which is the reflected light fromreference surface BS1 as the Fizeau reference surface, and the secondlight beam, which is the reflected light from reflecting surface MS1, isdetected at detector 434.

[0245] As discussed earlier, the focal point of concave reflectingmirror MO and the focal point of lens group FL coincide, in the statewherein folding mirrors M1, M2 are accurately aligned with respect tofirst lens barrel 401 and second lens barrel 403. Thus, the parallellight beam perpendicularly impinges reflecting surface MS1 of concavereflecting mirror MO. As a result, a predetermined interference fringebetween the reflected light from reference surface BS1 and the reflectedlight from concave reflecting mirror MO is detected in detector 434. Inother words, by jogging folding mirrors M1, M2 with respect to firstlens barrel 401 and second lens barrel 403 based on the interferencefringe detected in detector 434, folding mirrors M1, M2 can beaccurately aligned with respect to first lens barrel 401 and second lensbarrel 403.

[0246] Next, the alignment of folding mirrors M1, M2 with respect tofirst lens barrel 401 and second lens barrel 403 is explained.

[0247] In the present working example, folding mirrors M1, M2 areaccurately positioned with respect to support body 402 so that thereflecting surface of first folding mirror M1 and the reflecting surfaceof second folding mirror M2 are orthogonal. In addition, reflectingsurface MS2, which is parallel to the line of intersection between thereflecting surface of first folding mirror M1 and the reflecting surfaceof second folding mirror M2 accurately positioned so that they areorthogonal, is set with respect to support body 402. Positioning offolding mirrors M1, M2 and reflecting surface MS2 with respect tosupport body 402 is achieved easily with prior art that uses, forexample, an autocollimator (apparatus that detects angular displacementof a reflecting mirror by collimated light). The following brieflyexplains the positioning of reflecting surface MS2 and folding mirrorsM1, M2 with respect to support body 402, referencing FIG. 19a.

[0248] First, in FIG. 19a, folding mirrors M1, M2 are positioned withrespect to support body 402 so that the reflecting surface of firstfolding mirror M1 and the reflecting surface of second folding mirror M2are substantially orthogonal to a certain degree of accuracy. In thisstate, reflecting surface 441 a of reflecting member 441 is positionedso that it is substantially parallel to a certain degree of accuracy tothe line of intersection between the reflecting surface of first foldingmirror M1 and the reflecting surface of second folding mirror M2. Then,autocollimator 442 is installed at a position to collimate thereflecting surface of first folding mirror M1, and first plane parallelplate 443 is set using autocollimator 442 so that it is parallel toreflecting surface 441 a. Next, autocollimator 442 is moved to aposition to collimate reflecting surface MS2 of reflecting member 446attached to support body 402, and third plane parallel plate 445 is setusing autocollimator 442 so that it is parallel to reflecting surface441 a. Last, autocollimator 442 is moved to a position to collimate thereflecting surface of second folding mirror M2, and second planeparallel plate 444 is set using autocollimator 442 so that it isparallel to reflecting surface 441 a. In this manner, first planeparallel plate 443, second plane parallel plate 444 and third planeparallel plate 445 are set mutually parallel at the required accuracy.

[0249] In this state, reflecting member 441 is removed from the opticalpath, and the light from autocollimator 442 impinges on second foldingmirror M2 via second plane parallel plate 444. The light reflected bysecond folding mirror M2 is reflected by first folding mirror M1, andimpinges on first plane parallel plate 443. The light reflected by firstplane parallel plate 443 returns to autocollimator 442 via first foldingmirror M1, second folding mirror M2 and second plane parallel plate 444.In this case, since plane parallel plates 443, 444 are arrangedgeometrically parallel, the reflecting surface of first folding mirrorM1 and the reflecting surface of second folding mirror M2 can be madeorthogonal with high precision if the plane parallel plates 443, 444 areset optically parallel by jogging first folding mirror M1. In addition,by moving autocollimator 442 again to the position to collimatereflecting surface MS2 of reflecting member 446, and by usingautocollimator 442 to adjust reflecting surface MS2 of reflecting member446 so that it is parallel to third plane parallel plate 445, reflectingsurface MS2, which is parallel to the line of intersection between thereflecting surface of first folding mirror M1 and the reflecting surfaceof second folding mirror M2, can be set with high precision with respectto support body 402.

[0250] Generally, when performing alignment of first folding mirror M1and second folding mirror M2 with respect to first lens barrel 401 andsecond lens barrel 403 by moving or rotating as a single body firstfolding mirror M1 and second folding mirror M2, which are set so thattheir reflecting surfaces are mutually orthogonal, first folding mirrorM1 and second folding mirror M2 have five degrees of freedom foradjustment. Namely, these are movement (shift) in the Y direction,movement in the Z direction, rotation (tilt) about the X axis, rotationabout the Y axis and rotation about the Z axis. In contrast, the focalpoint position deviation information obtained by interferometer 421,namely the relative positional deviation information of the focal pointof lens group FL and the focal point of concave reflecting mirror MO, isof three types: positional deviation information in the x direction,positional deviation information in the y direction and positionaldeviation information in the z direction. Accordingly, z is the localcoordinate along optical axes Z1 to Z2, and x and y are the local axesparallel to the paper surface of each drawing in a plane perpendicularto the z axis, and are perpendicular local coordinates. In the presentmode for carrying out the present invention, by setting reflectingsurface MS2, which is parallel to the line of intersection between thereflecting surface of first folding mirror M1 and the reflecting surfaceof second folding mirror M2, perpendicular to the axis of first lensbarrel 801 along the Z axis, the number of degrees of freedom foradjustment needed with respect to first folding mirror M1 and secondfolding mirror M2 is reduced to three, comprising movement in the Ydirection, movement in the Z direction, and rotation about the Z axis.

[0251] Setting reflecting surface MS2 perpendicular to the axis of firstlens barrel 401 is easily achieved by the use of, for example, anautocollimator and the like. The following briefly explains thepositioning of reflecting surface MS2 with respect to the axis of firstlens barrel 401, referencing FIG. 17 and FIGS. 19a and 19 b. In thepresent mode for carrying out the present invention, a plane parallelplate perpendicular to the axis of first lens barrel 401 is installed atthe peripheral part of first lens barrel 401, and reflecting surface MS2is positioned perpendicular to the axis of first lens barrel 401 bysetting this plane parallel plate and reflecting surface MS2 parallel.Furthermore, since the two lens barrels 401, 403 are positioned so thatthe axis of first lens barrel 401 and the axis of second lens barrel 403are mutually parallel, as discussed earlier, the only way to setreflecting surface MS2 perpendicular to the axis of second lens barrel403 is by positioning reflecting surface MS2 with respect to the axis offirst lens barrel 401. Accordingly, it is understood that a planeparallel plate perpendicular to the axis of second lens barrel 403 maybe installed at the peripheral part of second lens barrel 403, and thatthis plane parallel plate and reflecting surface MS2 may be setparallel.

[0252] First, plane parallel plate 451 is positioned inside first lensbarrel 401 along the axis thereof, as shown in FIG. 19B. Furthermore,the explanation related to the setting of plane parallel plate 451perpendicular to the axis (optical axis Z1) of first lens barrel 401 isomitted. Then, autocollimator 452 is installed at a position tocollimate plane parallel plate 451, and autocollimator 452 is used toset plane parallel plate 453 parallel to plane parallel plate 451.

[0253] Next, autocollimator 452 is moved to a position to collimatereflecting surface MS2 and, using autocollimator 452, plane parallelplate 154 is installed at the peripheral part of first lens barrel 401so that it is parallel to plane parallel plate 453. In this state, planeparallel plate 453 is removed from the optical path, and support body402 is positioned and adjusted (see FIG. 18A) using autocollimator 452so that reflecting surface MS2 is parallel to reference surface BS2 ofplane parallel plate 454.

[0254] In this mariner, reflecting surface MS2 of support body 402 canbe set perpendicular to the axis of first lens barrel 401 and the axisof second lens barrel 403 along the Z axis. Namely, reflecting surfaceMS2 of support body 402 can be set parallel to the XY plane. In otherwords, it can be set so that the light impinging on first folding mirrorM1 along optical axis Z1 is reflected in the Y direction. As a result,the five degrees of freedom for adjustment, mentioned earlier, for firstfolding mirror M1 and second folding mirror M2 can be reduced to twodegrees of freedom for adjustment, comprising rotation about the X axisand rotation about the Y axis. In other words, the three degrees offreedom comprising movement in the Y direction, movement in the Zdirection and rotation about the Z axis, which correspond to the threetypes of positional deviation information comprising positionaldeviation information in the x direction, positional deviationinformation in the y direction and positional deviation information inthe z direction, should each be independently adjusted.

[0255] Generally, the relationship shown in condition (i) below holdsbetween change in wavefront aberration ΔW and wavefront deviations εX,εY, εZ between the first light beam, which is the reflected light fromreference surface BS1, and the second light beam, which is the reflectedlight from reflecting surface MS1 of concave reflecting mirror MO, (asdescribed in the reference by Kazumi Murata, entitled “Optics” ScienceCo., Section 1151):

ΔW=[ε _(z)/(8·(F _(FL))²)]−[(ε_(x)+ε_(y))/(2·F _(FL))]  (i)

[0256] Therein, F_(FL) is the F number of lens group FL as the Fizeaulens. In addition, εx, εy and εz are the positional deviations betweenthe center of curvature of the wavefront of the first light beam and thecenter of curvature of the wavefront of the second light beam in thelocal coordinate system x, y, z; namely, the wavefront deviations.

[0257] Referring to condition (i), the smaller (brighter) the F numberFFL of lens group FL, the greater is the detection sensitivity ofwavefront deviations εx, εy, εz. For example, if the change in wavefrontaberration ΔW that is detectable in the interferometer is 0.1 μm, bysetting the value of F number F_(FL) of lens group FL to less than 4,the wavefront deviations can be adjusted with an accuracy in units ofmicrons and, in turn, folding mirrors M1, M2 can be aligned with respectto lens barrels 401, 403 with an accuracy in units of microns. If Fnumber F_(FL) of lens group FL exceeds 4, the alignment accuracy becomeslarger than 10 microns, which is unsuitable as the alignment accuracy ina projection optical system of a projection exposure apparatus. Byfurther preferably setting the value of F number F_(FL) of lens group FLto less than 3, alignment of higher accuracy can be realized.

[0258] As described above, first and second folding mirrors M1, M2 inthe present working example can be aligned with high precision withrespect to first lens barrel 401 and second lens barrel 403 by joggingfirst folding mirror M1 and second folding mirror M2 as a single body sothat the focal length of the concave reflecting mirror MO installedinside first lens barrel 401 and the focal length of lens group FLinstalled inside second lens barrel 403 coincide. In other words, thirdoptical axis Z2, specified by the arrangement of first and secondfolding mirrors M1, M2, can be aligned with high precision with respectto optical axis Z1 of first lens barrel 401 and optical axis Z3 ofsecond lens barrel 403.

[0259] After first and second folding mirrors M1, M2 have been alignedwith high precision with respect to first lens barrel 401 and secondlens barrel 403 in the present mode for carrying out the presentinvention, manufacture of the optical system is completed by positioningeach optical member in first lens barrel 401 and second lens barrel 403.Namely, as shown in FIG. 17, after concave reflecting mirror MO has beenremoved from first lens barrel 401 and lens group FL has been removedfrom second lens barrel 403, each of the optical members L1 to L3, MO ispositioned inside and along the axis (namely, Z1) of first lens barrel401 based on reference point A, and each of the optical members L3 to L8is positioned inside and along the axis (namely, Z3) of second lensbarrel 403 based on reference point B.

[0260] The assembly with high precision of each of the optical membersinside each of the lens barrels while making the optical axis of each ofthe optical members coincide with an accuracy in units of microns withrespect to the axis of first lens barrel 401 and the axis of second lensbarrel 403 is well known in the prior art, and redundant explanation isherein omitted.

[0261] Thus, in an optical system having a folding member according tothe present mode for carrying out the present invention, the relativeposition of a plurality of lens barrels and a folding member havingdifferent axes, namely the relative position between each optical axisand the folding member, can be aligned with high precision and, as aresult, an optical system having a folding member can be manufacturedwith high precision.

[0262] In the mode for carrying out the present invention discussedabove, the present invention is applied to an alignment method andmanufacturing method of a catadioptric-type projection optical system.Nevertheless, the need to perform with high precision the alignment ofthe relative position between a folding member and a plurality of lensbarrels (in turn, a plurality of optical axes) is not limited to acatadioptric-type projection optical system, and is generally common toan optical system having a folding member. In other words, the presentinvention can be applied in the same manner as the working exampledescribed above even if a plurality of catoptric optical systemscomprising only catoptric optical members like concave reflectingmirrors are optically connected via one or a plurality of foldingmembers, or if a plurality of dioptric optical systems comprising onlydioptric optical members are optically connected via one or a pluralityof folding members.

[0263] In addition, in the mode for carrying out the present inventiondiscussed above, the present invention is applied to an optical systemwherein two lens barrels are arranged via two folding members. However,it will be understood that the present invention could also be appliedto an optical system wherein a plurality of lens barrels are arrangedvia one or three or more folding members.

[0264] In the working example discussed above, concave reflecting mirrorMO is installed inside first lens barrel 401 and lens group FL isinstalled inside second lens barrel 403. However, lens group FL may beinstalled in first lens barrel 401 and concave reflecting mirror MO maybe installed inside second lens barrel 403.

[0265] The present mode for carrying out the present invention discussedabove takes into consideration ease of adjustment, ease of ensuring therequired accuracy and the like, makes the axis of first lens barrel 401and the optical axis of concave reflecting mirror MO coincide and makesthe axis of second lens barrel 403 and the optical axis of lens group FLcoincide. In addition, reference point RA and the center of first lensbarrel 401 are made to coincide, and reference point RB and the centerof second lens barrel 403 are made to coincide. Nevertheless, referencepoints RA, RB are not necessarily set on the axis of first lens barrel401 and the axis of second lens barrel 403, and can be set to anarbitrary positional relationship with respect to first lens barrel 401and second lens barrel 403. In addition, the optical axis of concavereflecting mirror MO and the optical axis of lens group FL are notnecessarily made to coincide with the axis of first lens barrel 401 andthe axis of second lens barrel 403.

[0266] In the working example discussed above, the positional deviationbetween the focal point of lens group FL and the focal point of concavereflecting mirror MO is adjusted based on the interference between thefirst light beam and the second light beam detected by theinterferometer. Nevertheless, the positional deviation between the focalpoint of lens group FL and the focal point of concave reflecting mirrorMO can be detected based on the positional deviation between theconvergent point of the first light beam and the convergent point of thesecond light beam, without the use of an interferometer, and mirrors M1,M2 can subsequently be aligned with respect to lens barrels 401, 403.

[0267] Furthermore, when detecting the interference between the firstlight beam and the second light beam in the working example discussedabove, lens group FL that functions as a Fizeau lens is installed insidesecond lens barrel 403. Nevertheless, a zone plate having a known focallength can be used in place of lens group FL. In this case, the patternsurface of the zone plate comprises reference surface BS1.

[0268] According to the seventh mode for carrying out the presentinvention as discussed above, in an optical system having a foldingmember, the relative position between a plurality of lens barrels andthe folding member having different axes, namely the relative positionbetween each optical axis and the folding member, can be aligned withhigh precision. Furthermore, an optical system having a folding membercan be manufactured with high precision using this alignment method.

[0269] Next, a method of forming a predetermined circuit pattern on awafer using the projection exposure apparatus according to the presentinvention is explained, referencing flowchart 500 in FIG. 20.

[0270] First, in Step 502, a metal film is vapor deposited onto one lotof wafers. Next, in Step 504, photoresist is coated onto the metal filmon the wafers of the first lot. Subsequently, in Step 503, using aprojection exposure apparatus according to one of the configurations ofthe above modes for carrying out the present invention, the image of thepattern on reticle R is successively exposed and transferred onto eachexposure region on the wafers of that one lot. Afterwards, in Step 508,the photoresist on the wafers of that one lot is developed and then, inStep 510, the circuit pattern corresponding to the pattern on reticle Ris formed in each exposure region on each wafer. by etching with theresist pattern on the wafers of that one lot as the masks. Subsequently,devices like semiconductor devices having extremely fine circuits aremanufactured by further forming circuit patterns of upper layers, andthe like.

[0271] Ultraviolet light having a wavelength of 100 nm or greater, forexample, far ultraviolet (DUV) light like the g-line, the i-line or aKrF excimer laser, or vacuum ultraviolet (VUV) light like an ArF excimerlaser or an F₂ laser (wavelength of 157 nm) can be used as the exposureillumination light in the above modes for carrying out the presentinvention. In a scanning-type exposure apparatus that uses an F₂ laseras the light source, a catadioptric optical system is employed as theprojection optical system, as in the above modes for carrying out thepresent invention, the dioptric optical members (lens elements) used inthe illumination optical system or projection optical system are allmade of fluorite (CaF₂), the air inside the F₂ laser light source, theillumination optical system and the projection optical system isreplaced with helium gas, and the space between the illumination opticalsystem and the projection optical system and the space between theprojection optical system and the wafer are also filled with helium gas.In addition, in an exposure apparatus that uses an F₂ laser, a reticleis used that is made of at least one of fluorite, synthetic quartz dopedwith fluorine, magnesium fluoride or crystalline quartz. Furthermore, asthe dioptric optical member used in the projection optical system, atleast one type among the following materials can be used: fluorinecrystal materials like fluorite (calcium fluoride), barium fluoride(BaF), lithium fluoride (LiF), magnesium fluoride (MgF₂), lithiumcalcium aluminum fluoride (LiCaAlF₆), lithium strontium aluminumfluoride (LiSrAlF₆) and crystalline quartz synthetic quartz doped withfluorine and quartz doped with germanium, and the like.

[0272] The higher harmonics of a solid state laser like a YAG laserhaving an oscillation spectrum in, for, example, one of the wavelengthsof 248 nm, 193 nm or 157 nm, may be used in place of an excimer laser.

[0273] In addition, higher harmonics may also be used wherein a laser ofa single wavelength in the visible region or infrared region oscillatedfrom a DFB semiconductor laser or a fiber laser is amplified by a fiberamplifier doped with, for example, erbium (or, both erbium and indium),and the wavelength is then transformed to ultraviolet light using anon-linear optical crystal.

[0274] For example, if the oscillation wavelength of a single wavelengthlaser is in the range of 1.51 to 1.59 μm, then the eighth harmonic, thatgenerates wavelengths in the range of 189 to 199 nm, or the tenthharmonic, that generates wavelengths in the range of 451 to 159 nm, isoutput. In particular, if the oscillated wavelength is set within therange of 1.544 to 1.553 μm, then the eighth harmonic in the range of 193to 194 nm, namely ultraviolet light of substantially the same wavelengthas an ArF excimer laser, is obtained. If the oscillation wavelength isset in the range of 1.57 to 1.58 μm, then the tenth harmonic in therange of 157 to 158 nm, namely ultraviolet light of substantially thesame wavelength as an F₂ laser, is obtained.

[0275] If the oscillation wavelength is set in the range of 1.03 to 1.12μm, then the seventh harmonic, that generates wavelengths in the rangeof 147 to 160 μm, is output. In particular, if the oscillationwavelength is set in the range of 1.099 to 1.106 μm, then the seventhharmonic, that generates wavelengths in the range of 157 to 158 nm,namely ultraviolet light of substantially the same wavelength as an F₂laser, is obtained. An yttrium doped fiber laser may be used as thesingle wavelength oscillation laser.

[0276] The wavelength of the exposure illumination light in the abovemodes for carrying out the present invention is naturally not limited to100 nm or greater. For example, to expose a pattern with less than 70 nmwavelength light, EUV (extreme ultraviolet) light in the soft X-rayregion (for example, the 5 to 15 nm wavelength region) is generatedusing an SOR or a plasma laser as the light source, an EUV exposureapparatus is being developed that uses a catoptric-type reductionoptical system and a catoptric-type mask designed based on such anexposure wavelength (for example, 13.5 nm). Since a construction whereina folding member is applied to a catoptric-type reduction optical systemis also conceivable in this apparatus, this apparatus is also includedin the range of application of the present invention. The projectionoptical system may use -not only a reduction system, but also a unitymagnification system or an enlargement system (for example, an exposureapparatus and the like for manufacturing liquid crystal displays).

[0277] The present invention can be applied not only to exposureapparatuses used in the manufacture of semiconductor devices, but alsoto exposure apparatuses used in the manufacture of displays that includeliquid crystal displays and the like, those used in the manufacture ofthin film magnetic heads and exposure apparatuses that transfer adisplay pattern onto a glass plate, and those used in the manufacture ofimage pickup devices (CCDs and the like) and exposure apparatuses thattransfer a device pattern onto a ceramic wafer. In addition, the presentinvention can be applied to exposure apparatuses that transfer a circuitpattern onto a glass substrate or silicon wafer and the like in order tomanufacture a reticle or a mask.

[0278] As described above, the present invention is not limited to theabovementioned modes for carrying out the present invention, and it isunderstood that various configurations can be obtained in a range thatdoes not depart from the purport of the present invention.

1. A catadioptric projection optical system that makes first and secondplanes optically conjugate, including a plurality of lens surfaces andat least two reflecting surfaces, the catadioptric projection opticalsystem comprising: a catadioptric imaging optical subsystem; and arefractive imaging optical subsystem; wherein a position that isoptically conjugate to the first and second planes is formed in anoptical path between the catadioptric imaging optical subsystem and therefractive imaging optical subsystem; the catadioptric imaging opticalsubsystem is arranged in the optical path between the first plane andthe conjugate position; the refractive imaging optical subsystem isarranged in an optical path between the second plane and the conjugateposition; and the catadioptric imaging optical subsystem includes aconcave reflecting surface, an optical path between the first plane andthe concave reflecting surface, and an optical path between the concavereflecting surface and the refractive imaging optical subsystem; atleast one reflecting surface among the at least two reflecting surfacesis arranged in the optical path between the concave reflecting surfaceand the refractive imaging optical subsystem; at least one lens surfaceamong the plurality of lens surfaces has an aspherical shape; therefractive imaging optical subsystem includes a plurality of lenselements; and the plurality of lens elements in the refractive imagingoptical subsystem are positioned so that a light beam including amaximum numerical aperture of 0.75 can be guided to the second plane. 2.The catadioptric projection optical system according to claim 1, whereina reduced image of a first object located at the first plane is formedat the second plane.
 3. The catadioptric projection optical systemaccording to claim 2, further comprising: another reflecting surfacedifferent from the concave reflecting surface and the at least onereflecting surface; wherein the another reflecting surface is arrangedin the optical path between the first plane and the refractive imagingoptical subsystem.
 4. The catadioptric projection optical systemaccording to claim 3, wherein the first plane is parallel to the secondplane.
 5. The catadioptric projection optical system according to claim1, further comprising: another reflecting surface different from theconcave reflecting surface and the at least one reflecting surface;wherein the another reflecting surface is arranged in the optical pathbetween the first plane and the refractive imaging optical subsystem. 6.The catadioptric projection optical system according to claim 5, whereinthe first plane is parallel to the second plane.
 7. The catadioptricprojection optical system according to claim 5, wherein the at least onereflecting surface and the another reflecting surface are planarreflecting surfaces.
 8. The catadioptric projection optical systemaccording to claim 7, wherein the at least one reflecting surface andthe another reflecting surface are perpendicular to each other.
 9. Thecatadioptric projection optical system according to claim 5, wherein animage of the first plane is formed in a region on the second plane thatdoes not include an optical axis of the refractive imaging opticalsubsystem.
 10. The catadioptric projection optical system according toclaim 1, wherein the catadioptric imaging optical subsystem includes alens group positioned in the optical path between the first plane andthe concave reflecting surface.
 11. The catadioptric projection opticalsystem according to claim 10, wherein the lens group in the catadioptricimaging optical subsystem has a positive refractive power.
 12. Thecatadioptric projection optical system according to claim 11, whereinthe lens group in the catadioptric imaging optical subsystem is coaxialwith the concave reflecting mirror.
 13. The catadioptric projectionoptical system according to claim 10, further comprising: anotherreflecting surface different from the concave reflecting surface and theat least one reflecting surface; wherein the another reflecting surfaceis arranged in the optical path between the first plane and therefractive imaging optical subsystem.
 14. The catadioptric projectionoptical system according to claim 13, wherein the first plane isparallel to the second plane.
 15. The catadioptric projection opticalsystem according to claim 13, wherein the at least one reflectingsurface and the another reflecting surface are planar reflectingsurfaces.
 16. The catadioptric projection optical system according toclaim 15, wherein the at least one reflecting surface and the anotherreflecting surface are perpendicular to each other.
 17. The catadioptricprojection optical system according to claim 1, wherein an image of thefirst plane is formed in a region on the second plane which does notinclude an optical axis of the refractive imaging optical subsystem. 18.The catadioptric projection optical system according to claim 17,wherein a reduced image of an object the first plane is formed at a ¼reduction magnification on the second plane.
 19. A projection exposureapparatus that illuminates a mask, in which a predetermined pattern isprovided, by an illumination optical system and transfers a reducedimage of the pattern onto a substrate by a projection optical system,the projection exposure apparatus comprising: a mask stage thatpositions the mask at a first plane so that a normal line of a patternsurface of the mask is substantially in a direction of gravity; and asubstrate stage that positions the substrate at a second plane so that anormal line of the substrate is substantially in the direction ofgravity; wherein the projection optical system is provided with thecatadioptric projection optical system according to claim
 1. a
 20. Aprojection exposure method that illuminates a mask, in which apredetermined pattern is provided, by an illumination optical system andtransfers a reduced image of the pattern onto a substrate by aprojection optical system, the method comprising the steps of:positioning the mask at a first plane so that a normal line of a patternsurface of the mask is substantially in a direction of gravity;positioning the substrate at a second plane so that a normal line of thesubstrate is substantially in the direction of gravity; and forming thereduced image of the pattern onto the substrate by using thecatadioptric projection optical system as set forth in claim
 1. 21. Acatadioptric projection optical system including a plurality of lenssurfaces and at least three reflecting surfaces, and that forms areduced image of a first plane at a second plane, comprising: acatadioptric imaging optical subsystem; and a refractive imaging opticalsubsystem; wherein an intermediate image of the first plane is formed inan optical path between the catadioptric imaging optical subsystem andthe refractive imaging optical subsystem, the catadioptric imagingoptical subsystem is arranged in an optical path between the first planeand the intermediate image formation position, the refractive imagingoptical subsystem is arranged in an optical path between the secondplane and the intermediate image formation position, the catadioptricimaging optical subsystem includes a concave reflecting surface, anoptical path between the first plane and the concave reflecting surface,and an optical path between the concave reflecting surface and therefractive imaging optical subsystem, at least one reflecting surfaceamong the at least three reflecting surfaces is arranged in the opticalpath between the concave reflecting surface and the refractive imagingoptical subsystem, another reflecting surface among the at least threereflecting surfaces is arranged in the optical path between the firstplane and the refractive imaging optical subsystem, at least one lenssurface among the plurality of lens surfaces has an aspherical shape,the refractive imaging optical subsystem includes a plurality of lenselements, and the plurality of lens elements in the refractive imagingoptical subsystem are positioned so that a light beam including amaximum numerical aperture of 0.75 can be guided to the second plane.22. The catadioptric projection optical system according to claim 21,wherein the at least one reflecting surface and the another reflectingsurface are perpendicular to each other.
 23. The catadioptric projectionoptical system according to claim 22, wherein the at least onereflecting surface and the another reflecting surface are planarreflecting surfaces.
 24. The catadioptric projection optical systemaccording to claim 23, wherein the another reflecting surface isarranged in the optical path between the catadioptric imaging opticalsubsystem and the refractive imaging optical subsystem.
 25. Thecatadioptric projection optical system according to claim 21, wherein areduced image of an object on the first plane is formed in a region onthe second plane that does not include an optical axis of the refractiveimaging optical subsystem.
 26. A projection exposure apparatus thatilluminates a mask, in which a predetermined pattern is provided, by anillumination optical system and transfers a reduced image of the patternonto a substrate by a projection optical system, the projection exposureapparatus comprising: a mask stage that positions the mask at a firstplane so that a normal line of a pattern surface of the mask issubstantially in a direction of gravity; and a substrate stage thatpositions the substrate at a second plane so that a normal line of thesubstrate is substantially in the direction of gravity; wherein theprojection optical system is provided with the catadioptric projectionoptical system according to claim
 21. 27. A projection exposure methodthat illuminates a mask, in which a predetermined pattern is provided,by an illumination optical system and transfers a reduced image of thepattern onto a substrate by a projection optical system, the methodcomprising the steps of: positioning the mask at a first plane so that anormal line of a pattern surface of the mask is substantially in adirection of gravity; positioning the substrate at a second plane sothat a normal line of the substrate is substantially in the direction ofgravity; and forming a reduced image of the pattern onto the substrateby using the catadioptric projection optical system as set forth inclaim
 21. 28. A projection exposure apparatus that illuminates a mask,in which a predetermined pattern is provided, by an illumination opticalsystem and transfers a reduced image of the pattern onto a substrate bya projection optical system, the projection exposure apparatuscomprising: a mask stage that positions the mask at a first plane sothat a normal line of a pattern surface of the mask is substantially ina direction of gravity; a substrate stage which positions the substrateat a second plane so that a normal line of the substrate issubstantially in the direction of gravity; a catadioptric first imagingoptical system that includes a concave reflecting surface mirror and arefractive optical member, and forms an intermediate image of the firstplane; a refractive second imaging optical system that includes arefractive optical member and forms a reduced image of the intermediateimage at the second plane; a first optical path deflecting memberarranged in an optical path between the first plane and the secondimaging optical system and provided with a reflecting surface of whichan entire effective region is substantially planar; and a second opticalpath deflecting member arranged in an optical path between the firstplane and the second imaging optical system and provided with areflecting surface of which an entire effective region is substantiallyplanar; wherein the refractive optical members in the first and secondimaging optical systems, the concave reflecting surface mirror, and thefirst and second optical path deflecting members are positioned so thatthe reduced image is parallel to a pattern surface of the mask, and therefractive optical member of the second imaging optical system ispositioned to guide a light beam including a maximum numerical apertureof 0.75 to the second plane.
 29. The projection exposure apparatusaccording to claim 28, wherein a surface of at least one refractiveoptical member among the refractive optical members is formed in anaspherical shape.
 30. The projection exposure apparatus according toclaim 29, wherein: the first imaging optical system includes first andsecond lens groups; the first optical path deflecting member is arrangedin an optical path between the second lens group and the second imagingoptical system; and the second lens group and the concave reflectingsurface mirror are coaxially arranged.
 31. The projection exposureapparatus according to claim 30, wherein the first and second lensgroups are coaxially arranged.
 32. The projection exposure apparatusaccording to claim 28, wherein a surface of at least one refractiveoptical member among the refractive optical members in the secondimaging optical system is formed in an aspherical shape.
 33. Aprojection exposure method that illuminates a mask, in which apredetermined pattern is provided, by an illumination optical system andtransfers a reduced image of the pattern onto a substrate by aprojection optical system, the method comprising the steps of:positioning the mask at a first plane so that a normal line of a patternsurface of the mask is substantially in a direction of gravity;positioning the substrate at a second plane so that a normal line of thesubstrate is substantially in the direction of gravity; and forming areduced image of the pattern onto the substrate by using the projectionexposure apparatus as set forth in claim 28.